Dianil brown E, 1 lb. soda and 20 lb. salt.
_Dark Brown._--Dye with 1 lb. Dianil brown 3 G O, 3 lb. Dianil brown D,
1 lb. soda and 20 lb. salt.
_Dark Green._--Dye with 4 lb. Primuline, 1-1/2 lb. Dianil black C R, 1
lb. soda and 20 lb. salt.
_Walnut Brown._--Dye with 1 lb. Dianil brown 3 G O, 8 oz. Dianil brown
R, 3 lb. Dianil brown B D, 1 lb. soda, and 20 lb. salt.
_Light Green._--Dye with 3 lb. Primuline, 8 oz. Dianil blue B, 5 oz.
Dianil dark blue R, 1 lb. soda, and 20 lb. salt.
_Orange Yellow._--Dye with 3-1/4 lb. Primuline, 1 lb. Oxydianil yellow,
and 25 lb. salt.
_Olive._--Dye with 3-1/2 lb. Primuline, 8 oz. Dianil brown 3 G O, 8 oz.
Dianil blue B, 4 oz. Dianil dark blue R, 1 lb. soda, and 25 lb. salt.
_Bright Yellow._--Dye with 2 lb. Primuline, and 20 lb. salt.
_Gold Yellow._--Dye with 2 lb. Diamine fast yellow A, 1 lb. soda, and 20
lb. salt.
_Bright Walnut._--Dye with 1/2 lb. Diamine nitrazol brown B, 1 lb.
Oxydiamine orange R, 1 lb. soda, and 20 lb. Glauber's salt.
_Gold Brown._--Dye with 1/2 lb. Diamine nitrazol brown G, 1 lb.
Primuline, and 20 lb. salt.
_Green._--Dye with 2 lb. Primuline, 1 lb. Diamine nitrazol black B, 1
lb. soda and 20 lb. salt.
_Pale Chestnut._--Dye with 1 lb. Primuline, 1/2 lb. Oxydiamine orange R
and 20 lb. salt.
_Moss Brown,_--Dye with 2 lb. Primuline, 1 lb. diamine jet black O O and
20 lb. salt.
_Chocolate._--Dye with 1-1/2 lb. Diamine brown V, 2 lb. Diamine nitrazol
brown R D, 2 lb. soda and 20 lb. Glauber's salt.
_Olive Brown._--Dye with 2 lb. Diamine nitrazol brown G, 1 lb. Diamine
nitrazol black B, 1 lb. soda and 20 lb. Glauber's salt.
_Russian Green._--Dye with 2 lb. Diaminogene extra, 2 lb. soda and 20
lb. Glauber's salt.
_Bronze Green._--Dye with 2 lb. Diamine grey G, 2 lb. soda and 20 lb.
Glauber's salt.
_Terra-cotta Bed._--Dye with 2 lb. Oxydiamine orange R, 1 lb. soda and
20 lb. Glauber's salt.
_Terra-cotta Brown._--Dye with 2 lb. Diamine nitrazol brown R D, 1 lb.
soda and 20 lb. Glauber's salt.
_Olive Green._--Dye with 1 lb. Primuline, 2 lb. Diamine bronze G, 1 lb.
soda and 20 lb. Glauber's salt.
_Dark Green._--Dye with 1 lb. Primuline, 2 lb. Diamine nitrazol black B,
2 lb. soda and 20 lb. salt.
_Sage Brown._--Dye with 1 lb. Primuline, 2 lb. Diamine jet black O O, 1
lb. soda and 20 lb. salt.
_Black Brown._--Dye with 1 lb. Diamine brown V, 2 lb. Diamine nitrazol
black B, 2 lb. soda and 20 lb. Glauber's salt.
_Dark Walnut._--Dye with 1 lb. Diamine brown V, 2 lb. Oxydiamine orange
R, 2 lb. soda and 20 lb. Glauber's salt.
_Pale Sage._--Dye with 1 lb. Diamine brown V, 2 lb. Primuline, 1 lb.
soda and 20 lb. salt.
_Brown._--Prepare the dye-bath with 3 lb. Diamine jet black O O, 20 lb.
Glauber's salt, 2 lb. soda. Dye at the boil for one hour.
_Brown._--Prepare the dye-bath with 3/4 lb. Benzo nitrol brown G, 20 lb.
Glauber's salt, 2 lb. soda. Dye for one hour at the boil.
_Dark Brown._--Prepare the dye-bath with 2 lb. Benzo nitrol dark brown
N, 20 lb. Glauber's salt, 2 lb. soda. Dye for one hour at the boil.
_Brown._--Prepare the dye-bath with 4 lb. Direct fast brown B, 20 lb.
Glauber's salt, 2 lb. soda. Dye for one hour at the boil.
_Brown._--Prepare the dye-bath with 1 lb. 11 oz. Diamine jet black O O,
2 lb. Cotton brown N, 1 lb. 5 oz. Diamine brown V, 20 lb. Glauber's
salt, 2 lb. soda. Dye at the boil for one hour.
_Brown._--Prepare the dye-bath with 2 lb. Diamine bronze G, 6-1/2 oz.
Cotton brown N, 9-3/4 oz. Diamine fast yellow A, 20 lb. Glauber's salt,
2 lb. soda.
_Black._--Prepare the dye-bath with 5 lb. Pluto black B, 20 lb.
Glauber's salt, 2 lb. soda. Dye for one hour at the boil.
Solidogen A is a new coupler that has latterly been applied. It is a
syrupy liquid, and the coupling bath is made by taking from 4 lb. to 6
lb. of the Solidogen A, and 1 lb. to 2 lb. of hydrochloric acid, in
place of which 3 lb. to 5 lb. alum may be used. This bath is used at the
boil, the goods being treated for half an hour, then well rinsed and
dried. It increases the fastness of the colours to washing and soaping.
The following recipes show its application:--
_Bright Bed._--Dye with 3 lb. Dianil red 4 B, 2 lb. soap, 3 lb. soda and
15 lb. Glauber's salt, then fix with Solidogen A.
_Scarlet._--Dye with 3 lb. Dianil scarlet G, 2 lb. soda and 25 lb. salt;
fix with Solidogen A.
_Plum._--Dye with 3 lb. Dianil claret B, 5 lb. soda and 10 lb. Glauber's
salt, then fix with Solidogen A.
=Topping with Basic Dyes.=--The shades dyed with the direct dyes may be
materially brightened and new shades produced by topping with any of the
basic dyes, which are applied in a fresh warm bath. A great variety of
effects may be thus got of which the following recipes give a few
examples:--
_Green._--Dye with 1 lb. Titan yellow G and 20 lb. salt; top with 1/2
lb. Brilliant green.
_Blue._--Dye with 1-3/4 lb. Diamine azo blue R, 1 lb. soda and 20 lb.
Glauber's salt, then top with 2 oz. New Methylene blue N.
_Bright Blue._--Dye with 3/4 lb. Diamine brilliant blue G, 1 lb. soda
and 10 lb. Glauber's salt; top with 2 oz. New Methylene blue 3 R.
_Blue._--Dye with 1 lb. Diamine sky blue, 1 lb. soda and 10 lb.
Glauber's salt, and top with 4 oz. Brilliant green.
_Bose Lilac._--Dye with 1-1/2 oz. Diamine violet N, 1 lb. soda and 10
lb. Glauber's salt, then top with 2 oz. Tannin heliotrope.
_Green._--Dye at the boil for one hour with 2 lb. Benzo green G and 10
lb. Glauber's salt, then top in a fresh bath with 1/2 lb. Turquoise blue
B B.
_Violet._--Dye with 5 oz. Diamine violet N, 2 oz. Diamine brilliant blue
G, 1 lb. soda and 10 lb. salt, and top with 1 oz. Methyl violet 2 B.
_Plum._--Dye with 1-1/2 lb. Oxydiamine violet B, 5 oz. Diamine red 10 B,
2 lb. soda and 10 lb. Glauber's salt, then top with 1-1/2 oz. Methyl
violet R.
_Bright Green._--Dye with 1-1/4 lb. Diamine green G, 1-1/4 lb.
Oxydiamine yellow G G, 2 lb. soda and 10 lb. Glauber's salt, then top
with 2 oz. Brilliant green.
_Blue._--Dye with 2 lb. Benzo azurine G, 3 oz. Brilliant azurine B, 1
lb. soda and 20 lb. Glauber's salt, topping with 6 oz. Turquoise blue G
and 3 oz. New Victoria blue B.
_Dark Lilac._--Dye with 3-3/4 lb. Heliotrope B B, 1 lb. soda and 20 lb.
Glauber's salt, then top with 1 lb. Methyl violet R, and 1/2 lb. Methyl
violet 3 R.
_Scarlet._--Dye with 3 lb. Brilliant Congo R, 3 lb. soda and 20 lb.
Glauber's salt, then top with 8 oz. Safranine.
_Bright Green._--Dye with 3 lb. Chrysamine G, 2 lb. soap and 10 lb.
phosphate of soda, topping with 3/4 lb. Malachite green.
_Bright Violet._--Dye with 1-1/2 lb. Chicago blue 6 B, 1 lb. soda and 20
lb. Glauber's salt, topping with 10 oz. Methyl violet B.
_Dark Green._--Dye with 2 lb. Columbia green, 3 lb. soda and 10 lb.
Glauber's salt, topping with 10 oz. Malachite green.
_Claret._--Prepare a dye-bath with 3/4 oz. Diamine black R O, 2-1/2 lb.
Benzo purpurine 6 B, 10 lb. Glauber's salt. Dye at the boil for one
hour, then enter in a fresh cold bath of 1/2 lb. Safranine G. Work for
twenty minutes, lift, wash and dry.
_Seal Brown._--Make up a dye-bath with 2 lb. Benzo azurine G, 20 lb.
Glauber's salt. Enter yarn at 180° F., dye at the boil for one hour,
lift, wring, and enter into a fresh bath of 1-1/2 lb. Bismarck brown.
Work for one hour at about 180° F., lift, rinse well and dry.
(6) DYEING ON TANNIC MORDANT.
The oldest group of coal-tar dyes are the basic dyes, of which Magenta,
Brilliant green, Chrysoidine, Bismarck brown, Auramine are typical
representatives. For a long time these dyes were only used for dyeing
wool and silk; for cotton, linen, and some other vegetable fibres they
have little or no affinity, and hence cannot dye them direct. However,
it was found out that if the cotton be prepared or mordanted (as it is
called) with tannic acid or with any substance containing that compound
they could be used for dyeing cotton.
The mordant used, tannic acid, has the property of combining with the
dyes of this group to form insoluble coloured tannates. Now tannic acid
has a certain amount of affinity for cotton, if the latter be immersed
in solution of tannic acid or any material containing it some of the
latter is taken up and more or less fixed by the cotton fibre. Tannic
acid is a vegetable product found in a large number of plants, and plant
products, such as sumac, myrabolams, divi-divi, galls, oak bark,
gambier, cutch, algarobilla, valonia, etc., which are commonly known as
tannins, or tannin matters, on account of their use in the conversion of
animal skins or hides into leather, which is done in the tanning
industry.
By itself the tannin-colour lake, which may be formed on the cotton
fibre by immersion first in a bath of tannin and then in a dye-bath, is
not fast to washing and soaping, but by taking advantage of the fact
with such metals as tin, iron, antimony, etc., it combines to form
insoluble tannates; the tannic acid can be fixed on the cotton by
immersion in a bath containing such fixing salts as tartar emetic, tin
crystals, copperas, antimony fluoride, and antimony oxalate. The dyeing
of cotton with the basic colours therefore resolves itself into three
operations:--
(1) Tanning with tannic acid or some tanning matters.
(2) Fixation with tartar emetic or other fixing agent.
(3) Dyeing with the required colour or mixture of colours.
(1) =The Tanning Operation.=--The practice of tanning or mordanting
cotton with tannin is variously carried on by dyers. Some steep the
cotton in the tannin bath over night, others immerse it from two to
three hours in a lukewarm bath, while some enter it in a boiling bath,
which is then allowed to cool down and the cotton is lifted out. The
last is perhaps the quickest method, and experiments have shown that it
is as good as any other method, if the quantity of tannic acid taken up
be regarded as the criterion of success.
In the natural products which have just been enumerated, the tannic acid
is accompanied by some colouring matter, which is also absorbed by the
cotton; in some (sumac and galls) this colour is present in but small
quantities; in others (divi-divi, myrabolams, algarobilla), there is a
large quantity; therefore cotton treated with these comes out more or
less coloured. Now it is obvious that such forms of tannin cannot be
used when light tints are to be dyed, for such the acid itself must be
used, for medium shades sumac or galls may be used; while when dark
shades--browns, maroons, dark greens, navy blues, etc., are to be dyed,
then such tannin matters as divi-divi or myrabolams may be conveniently
and economically adopted. The quantity used varies according to
circumstances; the character of the shades that are to be dyed, the
dye-stuff used, the quality and character of the tannin matter used. For
pale shades about 1 per cent. of tannic acid may be used, deep shades
require from 3 to 4 per cent. Of tannin matters from 5 per cent. may be
used for pale shades, from 20 to 25 per cent. for deep shades. The
tannin baths are not exhausted, and may be kept standing, adding for
each succeeding lot of cotton from 1/2 to 3/4 of the above quantities of
tannin matters. Of course sooner or later the baths become unusable from
various causes, and then they may be thrown away; but old tannin baths
often work better than the new ones.
(2) =The Fixing Bath.=--Following on the tannin bath comes the fixing
bath to fix the tannin on the cotton in the form of insoluble metallic
tannates. A variety of metallic salts may be used for this purpose,
those of antimony, tin, iron, lead, etc., the substances most commonly
used being tartar emetic, antimony fluoride, oxalate of antimony, tin
crystals and copperas.
Beyond forming the insoluble tannate of antimony or tin, as the case may
be, the salts of antimony and tin have no further effect on the tanned
cotton, and they may be used to fix the tannin for all tints or shades,
from very pale to very deep. Of all these salts tartar emetic has been
found to be the best, probably because it is the least acid in its
reactions, and therefore there is no tendency to remove any tannin from
the fibre, as is the case with the other salts. Tin salt is little used
for this purpose, because of its acidity, which prevents it from fixing
the tannin as completely as is the case with tartar emetic.
With copperas or iron liquor the question comes up not only of the mere
fixation of the tannin, but also the fact that iron forms with tannin
grey to black compounds, hence cotton which has been tanned and then
immersed in a bath of copperas becomes coloured grey to black, according
to the quantity of the tannin matter used. The property is useful when
dark shades of maroons, clarets, greens, browns, blues, etc., are to be
dyed, and is frequently employed.
(3) =Dyeing.=--After the tannin and fixing operations comes the dyeing.
This is not by any means a difficult operation. It is best carried out
by preparing a cold bath, entering the prepared or mordanted cotton in
this and heating slowly up. It is not necessary to raise to the boil nor
to maintain the dye-bath at that heat, a temperature of 180° F. being
quite sufficient in dyeing with the basic colours, and the operation
should last only until the colouring matter is extracted from the
dye-bath. Working in this way, level uniform shades can be got.
One source of trouble in the dyeing of basic dyes, more especially with
magentas, violets and greens, lies in their slight solubility and great
strength. In preparing solutions of such dyes it is best to dissolve the
dye-stuff by pouring boiling water over it, and stirring well until all
appears to be dissolved.
This solution should be strained through a fine cloth, as any
undissolved specks will be sure to fix themselves on the cloth and lead
to dark spots and stains, as, owing to the weak solubility of the dye,
and this being also fixed as insoluble tannate by the tannic acid on the
fibre, there is no tendency for the dye to diffuse itself over the
cloth, as occasionally happens in other methods of dyeing. No advantage
is gained by adding to the dye-bath such substances as common salt or
Glauber's salt.
Some few of the dyes, _e.g._, Soluble blue, Victoria blue, which will
dye on a tannic mordant, are sulphonated compounds of the colour base.
These can be dyed in medium or light shades on to unmordanted cotton
from a bath containing alum, and in the ordinary method of dyeing the
addition of alum is beneficial, as tending to result in the production
of deep shades. These are somewhat faster to washing and soaping, which
is owing to the dye-stuff combining with the alumina in the alum to form
an insoluble colour lake of the sulphuric acid groups it contains.
Many recipes can be given for the dyeing of basic dyes on cotton; for
the range of tints and shades of all colours that can be produced by
their means is truly great. Typical recipes will be given showing what
basic dyes are available and how they can be combined together. The
dyer, however, who knows how to produce shades by combining one
dye-stuff with another is able to get many more shades than space will
permit to be given here.
_Sky Blue._--Mordant with 1 lb. tannic acid and 1/2 lb. tartar emetic,
then dye with 2-1/2 oz. Victoria blue B, and 1/2 oz. Turquoise blue G.
_Bright Blue._--Mordant with 2 lb. tannic acid and 1-1/2 lb. tartar
emetic, then dye with 1-1/2 lb. New Victoria blue B, and 3/4 lb.
Turquoise blue G.
_Pale Green._--Mordant with 1-1/2 lb. tannic acid and 1/4 lb. tartar
emetic, then dye with 1/4 oz. Brilliant green and 1/2 oz. Auramine I I.
_Bright Green._--Mordant with 1 lb. tannic acid and 1 lb. tartar emetic,
then dye with 6 oz. Brilliant green and 8 oz. Auramine I I.
_Turquoise Blue._--Mordant with 2 lb. tannic acid and 1-1/2 lb. tartar
emetic; dye with 1 lb. Turquoise blue G.
_Crimson._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, then
dye with 1-1/4 lb. Brilliant rhoduline red B and 5 oz. Auramine I I.
_Bright Violet._--Mordant with 2 lb. tannic acid and 1 lb. tartar
emetic; dye with 1-1/4 lb. Rhoduline violet and 3 oz. Methyl violet B.
_Rose Lilac._--Mordant with 2 lb. tannic acid and 1 lb. tartar emetic;
dye with 3/4 lb. Rhoduline violet.
_Yellow._--Mordant with 3 lb. tannic acid and 2-1/2 lb. tartar emetic;
dye with 2 lb. Auramine I I.
_Orange._--Mordant with 3 lb. tannic acid and 2-1/4 lb. tartar emetic;
dye with 2 lb. Chrysoidine.
_Green._--Mordant with 3 lb. tannic acid and 2-1/2 lb. tartar emetic,
then dye with 2 lb. Brilliant green.
_Red Violet._--Mordant with 1-1/2 lb. tannic acid and 1-1/4 lb. tartar
emetic, then dye with 8 oz. Methyl violet 4 R.
The same method may be followed with all the brands of Methyl, Paris and
Hoffmann violets, and so a range of shades from a purple to a pure
violet can be dyed. The 4 R to R brands of these violets dye reddish
shades, the redness decreasing according to the mark, the B to 6 B
brands dye bluish shades, the blueness increasing till the 6 B brand
dyes a very blue shade of violet.
_Bright Sea-Green._--Mordant with 1 lb. tannic acid and 1/2 lb. tartar
emetic, then dye with 2 oz. Turquoise blue G and 1/4 oz. New Victoria
blue B. With these two blues a very great variety of tints and shades of
blue can be dyed.
_Sea Green._--Mordant with 1 lb. tannic acid and 3/4 lb. tartar emetic,
and dye with 2 oz. Malachite green.
_Dark Green._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic,
then dye with 1-1/4 lb. Malachite green and 3/4 oz. Auramine I I.
By combination of Brilliant green or Malachite green (which are the
principal basic greens) with Auramine in various proportions a great
range of greens of all tints and shades, from pale to deep and from very
yellow to very green tints, can be dyed.
_Scarlet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, then
dye with 1-1/2 lb. Rhodamine 6 G and 1/4 lb. Auramine I I.
_Pink._--Mordant with 1 lb. tannic acid and 3/4 lb. tartar emetic, and
dye with 1/4 lb. Rhodamine G.
_Pink._--Mordant with 1 lb. tannic acid and 3/4 lb. tartar emetic, and
dye with 1/2 lb. Irisamine G.
_Slate Blue._--Mordant with 1-1/2 lb. tannic acid and 1 lb. tartar
emetic, then dye with 3/4 lb. Victoria blue B and 2 oz. Malachite green.
_Indigo Blue._--Mordant with 3 lb. tannic acid and 2-1/2 lb. tartar
emetic, then dye with 1 lb. Methylene blue 2 B and 1/2 lb. Malachite
green.
_Dark Scarlet._--Mordant with 3 lb. tannic acid and 2-1/2 lb. tartar
emetic, then dye with 1 lb. Safranine prima and 1/2 lb. Auramine I I.
_Grey._--Mordant with 1 lb. tannic acid and 1/2 lb. tartar emetic, then
dye with 1/2 lb. New Methylene grey B.
_Bluish Rose._--Mordant with 2 lb. tannic acid and 1 lb. tartar emetic,
then dye with 1 lb. Rhodamine B.
_Maroon._--Mordant with 4 lb. tannic acid and 2 lb. tartar emetic, and
dye with 2 lb. Magenta and 1/2 lb. Auramine.
_Dark Green._--Mordant with 5 lb. tannic acid and 2-1/2 lb. tartar
emetic, and dye with 1/2 lb. Methylene blue B B, 1/2 lb. Methyl violet 2
B and 2-1/2 lb. Auramine I I.
_Orange._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, and
dye with 1 lb. New Phosphine G.
_Lilac Grey._--Mordant with 1 lb. tannic acid and 1-1/2 lb. tartar
emetic, and dye with 1/4 lb. Methylene grey B F.
_Gold Brown._--Mordant with 3 lb. tannic acid and 1-1/2 lb. tartar
emetic, and dye with 3/4 lb. Thioflavine T and 3/4 lb. Bismarck brown.
_Orange._--Mordant with 2 lb. tannic acid and 1 lb. tartar emetic, and
dye with 1 lb. Auramine and 1/4 lb. Safranine.
_Dark Blue._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic,
and dye with 2-1/4 lb. New Methylene blue R and 3/4 lb. Naphtindone B B.
_Olive Green._--Mordant with 5 lb. sumac extract and 2 lb. copperas, and
dye with 1 lb. Auramine.
_Russian Green._--Mordant with 5 lb. sumac extract and 2 lb. copperas,
and dye with 2 lb. Malachite green.
_Scarlet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, and
dye with 1-1/2 lb. Thioflavine T and 1/2 lb. Irisamine G. With these two
dye-stuffs it is possible to produce a variety of useful shades from a
pure greenish yellow, with Thioflavine T alone, to a bright bluish
pink, with the Irisamine alone, through orange, scarlet, etc., with
combinations of the two dye-stuffs.
_Dark Grey._--Mordant with 5 lb. sumac extract and 3 lb. copperas, then
dye with 1 lb. New Methylene grey G.
_Blue Black._--Mordant with 8 lb. sumac extract and 4 lb. copperas, or
better with iron liquor, then dye with 2 lb. Indamine blue N.
_Olive Brown._--Mordant with 5 lb. sumac extract and 3 lb. copperas, and
dye with 1-1/2 lb. New Phosphine G.
_Indigo Blue._--Mordant with 1-1/2 lb. tannic acid and 1 lb. tartar
emetic; dye with 1/2 lb. New Methylene blue N.
_Sky Blue._--Mordant with 1/2 lb. tannic acid and 3/4 lb. tartar emetic;
dye with 1-1/2 oz. New Methylene blue G G.
_Dark Violet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic,
then dye with 4 lb. Fast neutral violet B.
_Bright Yellow._--Mordant with 2 lb. tannic acid and 1 lb. tartar
emetic, and dye with 2 lb. Thioflavine T.
_Primrose Yellow._--Mordant with 1 lb. tannic acid and 1/4 lb. tartar
emetic, and dye with 2 oz. Thioflavine T.
_Navy Blue._--Mordant with 5 lb. sumac extract and 3 lb. copperas, then
dye with 2 lb. New Methylene blue R.
_Violet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, and
dye with 2 lb. New Methylene blue 3 R.
_Dark Blue._--Mordant with 5 lb. sumac extract and 3 lb copperas, and
dye with 2 lb. New Methylene blue N X.
_Blue Black._--Mordant with 8 lb. sumac extract and iron liquor, then
dye with 3 lb. Metaphenylene blue B.
_Emerald Tint._--Mordant the cotton in the usual way with 1 lb. tannic
acid and 1 lb. tartar emetic; dye to shade at 180° F. in a bath
containing 14 oz. Auramine G, 2 oz. Brilliant green, then lift, wash and
dry.
_Orange._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, then
dye with 4 lb. Tannin orange R.
_Scarlet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic, and
dye with 2 lb. Tannin orange R and 1 lb. Safranine S.
_Dark Scarlet._--Mordant with 3 lb. tannic acid and 2 lb. tartar emetic,
and dye with 1/2 lb. Tannin orange R and 2 lb. Safranine S.
The Janus colours are a series of dyes of a basic nature which can be
applied somewhat differently to the ordinary basic dyes, although the
ordinary method can be followed. With these Janus dyes a two-bath
process is followed. A dye-bath is prepared containing the dye-stuff,
sulphuric acid and common salt, and this is used at the boil from half
to three-quarters of an hour, and the goods are allowed to remain in
another three-quarters of an hour while the bath cools down. Next the
dyed goods are run in a fixing bath of sulphuric acid, tannic acid and
tartar emetic, this is used at the boil from half to one hour, after
which the dyed goods are taken out and washed. If necessary the goods
may be now topped with basic colours in order to produce any desired
shade. The following recipes will show how the Janus dyes may be used:--
_Blue._--Dye with 9 oz. sulphuric acid, 8 oz. Janus blue G, and 5 lb.
common salt; fix with 3/4 lb. sulphuric acid, 8 oz. tannic acid and 4
oz. tartar emetic.
_Turquoise Blue._--Dye with 9 oz. sulphuric acid, 1 lb. Janus green B
and 10 lb. salt, fixing with 3/4 lb. sulphuric acid, 1 lb. tannin and
1/2 lb. tartar emetic.
_Dark Blue._--Dye with 9 oz. sulphuric acid, 2-1/2 lb. Janus blue R and
15 lb. common salt; fix with 3/4 lb. sulphuric acid, 2-1/2 lb. tannic
acid and 1-1/4 lb. tartar emetic.
_Buff._--Dye with 9 oz. sulphuric acid, 2 oz. Janus yellow R and 3 lb.
salt; fix with 3/4 lb. sulphuric acid, 3 oz. tannic acid and 3 lb.
tartar emetic.
_Crimson._--Dye with 9 oz. sulphuric acid, 2-1/2 lb. Janus red B and 15
lb. salt, fixing with 3/4 lb. sulphuric acid, 2-1/2 lb. tannic acid and
1-1/4 lb. tartar emetic.
_Red Violet._--Dye with 9 oz. sulphuric acid, 1 lb. Janus claret red B
and 10 lb. salt; fix with 12 oz. sulphuric acid, 1 lb. tannic acid and
1/2 lb. tartar emetic.
_Orange._--Dye with 9 oz. sulphuric acid, 1 lb. Janus yellow R and 10
lb. salt; fix with 12 oz. sulphuric acid, 1 lb. tannic acid and 1/2 lb.
tartar emetic.
_Dark Violet._--Dye with 9 oz. sulphuric acid, 2 lb. Janus grey B and 15
lb. salt; fix with 12 oz. sulphuric acid, 2-1/2 lb. tannic acid and
1-1/4 lb. tartar emetic.
_Chocolate Brown._--Dye with 9 oz. sulphuric acid, 3-1/2 lb. Janus brown
B and 15 lb. salt, fixing with 2 oz. sulphuric acid, 2-1/2 lb. tannic
acid and 1 lb. tartar emetic.
(6) DYEING ON METALLIC MORDANTS.
There are a number of dye-stuffs or colouring matters like alizarine,
logwood, fustic, barwood, cutch, resorcine green, etc., which have no
affinity for the cotton fibre, and of themselves will not dye it. They
have the property of combining with metallic oxides such as those of
iron, chromium, aluminium, tin, lead, calcium, etc., to form coloured
bodies which are more or less insoluble in water. These coloured bodies
are called "colour lakes," and the metallic compounds used in connection
with their production "mordants," hence often the dye-stuffs applied by
this method are termed "mordant dyes". In the case of the natural
dye-stuffs--logwood, fustic, Persian berries, Brazil wood, camwood,
cochineal, quercitron, cutch, etc.--which belong to this group of
"mordant dyes," the whole of the material does not enter into the
operation, but only a certain constituent contained therein, which is
commonly soluble in boiling water, and extracted out by boiling. This
constituent is called the "colouring principle" of the dye-stuff or
wood, and naturally varies with each. It is not intended here to deal
in detail with these colouring principles. The methods of applying and
the colours which can be got from these dyes varies very much. Roughly,
the modes of application fall under three heads: (1) the particular
metallic mordant is first fixed on the fibre by any suitable method, and
then the fibre is dyed; (2) the dye-stuff is first applied to the fibre,
and then the colour is fixed and developed by treatment with the
mordant; and (3) the dye-stuff and the mordant are applied at the same
time. This last method is not much used. In the following sections many
examples of these methods will be given.
The dyes fixed with metallic mordant vary in their composition and
properties. There is first the group of eosine dyes, which are acid
derivatives of a colour-base, and, in virtue of being so, will combine
with the metallic oxides. The colour of these colour lakes is quite
independent of what oxide is used, depending only on that of the
particular eosine dye employed. Then there are some members of the azo
dyes, particularly the croceine scarlets, which can also be dyed on the
cotton by the aid of tin, lead or alum mordants. Here, again, the
mordant has no influence on the colour, but only fixes it on the cotton.
The most important class of dye-stuffs which are dyed on to cotton with
a metallic mordant is that to which the term "mordant dyes" is now
given. This includes such dyes as logwood, fustic, madder, alizarine,
and all the dyes derived from anthracene. Many of these are not really
dyes, that is, they will not of themselves produce or develop a colour
on to any fibre when used alone; it is only when they combine with the
mordant oxide which is used, and then the colour varies with the
mordant. Thus, for instance, logwood with iron produces a bluish black;
with chrome, a blue; with alumina, a reddish blue. Alizarine with iron
produces a dark violet; with alumina, a scarlet; with chrome, a red;
with tin, a bright scarlet. Fustic gives with tin and alumina, bright
yellows; with chrome, a dark yellow; with iron, an olive, and so on with
other members of this group, of which more will be said later on.
_Dyeing with Eosines._
At one time a fairly large quantity of cotton was dyed with the eosines,
owing to the brightness of the shades given by them; but the
introduction of such direct dyes as the Erikas, Ceranines, etc., has
thrown the eosines out of use.
The method adopted for the production of eosine pinks and scarlets on
cotton involves three operations: (1) impregnating the cloth with sodium
stannate; (2) fixing oxide of tin by a bath of weak sulphuric acid; and
(3) dyeing with the eosine.
=(1) Preparing with Sodium Stannate.=--A bath of 8° Tw. is prepared, and
the cotton is allowed to steep in this bath until it becomes thoroughly
impregnated, after which it is taken out and wrung.
=(2) Fixing the Tin Oxide.=--A bath of sulphuric acid of 2° to 4° Tw. is
prepared, and the cotton is sent through it, after which it is washed
well with water, when it is ready for dyeing.
Stannate of soda is easily decomposed by acids; even the carbonic acid
present in the air will bring about this change. The tin contained in
the stannate is deposited on the cotton in the form of stannic oxide,
or, more strictly, stannic acid. As this is somewhat soluble in acids,
it is important that the sulphuric acid bath be not too strong, or there
will be a tendency for the tin oxide to be dissolved off the cotton, and
then but weak shades will be obtained in the final operation of dyeing.
Further, owing to the decomposition of the stannate by exposure to the
air, it is important that the substance should be used while fresh, and
that only fresh baths should be used.
=(3) Dyeing with Eosine Colours.=--After the treatment with stannate of
soda and sulphuric acid the prepared cotton is ready for dyeing. This
process is carried out by preparing a cold bath with the required
dye-stuff, entering the cotton therein, and then slowly raising to about
180° F., and maintaining at that heat until the desired shade is
obtained. It is not needful to raise to the boil and work at that heat.
No better results are obtained, while there is even a tendency for
colours to be produced that rub badly, which is due to the too rapid
formation of the colour lake; and it is worthy of note that when a
colour lake is rapidly formed on the fibre in dyeing it is apt to be but
loosely fixed, and the colour is then loose to both washing and rubbing.
* * * * *
_Dyeing with Acid and Azo Dyes._
In dyeing with this class of colours stannate of soda, acetate of lead
or alum may be used as mordants. The stannate of soda is employed in the
same manner as when the eosines are used, and, therefore, does not
require to be further dealt with.
Acetate of lead is used in a similar way. The cotton is first steeped in
a bath of acetate of lead of about 10° Tw. strong, used cold, and from
half an hour to an hour is allowed for the cotton to be thoroughly
impregnated with the lead solution, it is then wrung and passed a second
time into a bath of soda, when lead oxide or lead carbonate is deposited
on the cotton. After this treatment the cotton is ready for dyeing with
any kind of acid, azo and even eosine dyes, and this is done in the same
manner as is used in dyeing the eosines on a stannate mordant. The
shades obtained on a lead mordant cannot be considered as fast; they
bleed on washing and rub off badly.
When alum is used as the mordant it may be employed in the same way as
acetate of lead, but as a rule it is added to the dye-bath direct, and
the dyeing is done at the boil. This latter method gives equally good
results, and is more simple.
The eosines and erythrosines, water blues, soluble blues, croceine
scarlets, cloth scarlets, and a few other dyes of the azo and acid
series are used according to this method. The results are by no means
first class, deep shades cannot be obtained, and they are not fast to
washing, soaping and rubbing.
The methods of employing the much more important group of colouring
matters known as the mordant dyes, which comprise such well-known
products as logwood, fustic and alizarine, require more attention. With
these, alumina, iron, and chromium mordants are used as chief mordants,
either alone or in combination with one another, and with other bodies.
The principal point is to obtain a good deposit of the mordant on the
cotton fibre, and this is by no means easy.
There are several methods by the use of which a deposit is formed of the
mordant, either in the form of metallic oxide (or, perhaps, hydroxide)
or of a basic salt. In some cases the cotton is passed through alternate
baths containing, on one hand, the mordanting salt, _e.g._, alum,
copperas, etc., and, on the other, a fixing agent, such as soda or
phosphate of soda. Or a mordanting salt may be used, containing some
volatile acid that on being subjected to a subsequent steaming is
decomposed. Both these methods will be briefly discussed.
* * * * *
_Methods of Mordanting._
The cotton is first steeped in a bath containing Turkey-red oil, and is
then dried. By this means there is formed on the fibre a deposit of
fatty acid, which is of great value in the subsequent dyeing operations
to produce bright and fast shades. After the oiling comes a bath of alum
or alumina sulphate, either used as bought, or made basic by the
addition of soda. The result is to bring about on the fibre a
combination of the fatty acid with the alumina. Following on the alum
bath comes a bath containing soda or phosphate of soda, which brings
about a better fixation of the alumina.
These operations may be repeated several times, especially when a full
shade having a good degree of fastness is desired, as, for instance,
Turkey-reds from Alizarine. This method of mordanting is subject to
considerable variations as regards the order in which the various
operations are carried out, the strength of the baths, and their
composition. A great deal depends upon the ultimate result desired to be
obtained, and the price to be paid for the work.
Iron is much easier to fix on cotton than is either alumina or chrome.
It is usually sufficient to pass the cotton through a bath of either
copperas or iron liquor, hang up to dry or age, and then pass into a
bath of lime, soda or even phosphate of soda. The other mordants require
two passages to ensure proper deposition of the mordant on the fibre.
Following on the mordanting operations comes the dyeing, which is
carried out in the following manner. The bath is made cold with the
required amount of dye-stuff and not too small a quantity of water, the
cotton is immersed and worked for a short time to ensure impregnation,
then the temperature is slowly raised to the boil. This operation should
be carefully carried out, inasmuch as time is an important element in
the dyeing with mordant colours; the colouring principle contained in
the dye-stuff must enter into a chemical combination with the mordant
that has been fixed on the fibre. Heat greatly assists this being
brought about, but if the operation is carried on too quickly, then
there is a tendency for uneven shades to be formed. This can only be
remedied by keeping the temperature low until the dye-stuff has been
fairly well united with the mordant, and then maintaining the heat at
the boil to ensure complete formation of the colouring lake on the
fibre, and therefore the production of fast colours.
It has been noticed in the dyeing of alizarines on both cotton and wool
that when, owing to a variety of circumstances, local overheating of the
bath happens to take place dark strains or streaks are sure to be
formed. To avoid these care should be taken that no such local heating
can occur.
It only remains to add that it is possible to dye a great range of
shades by this method, reds with alizarine and alumina; blacks with
logwood and iron; greens from logwood, fustic, or Persian berries, with
chrome and iron; blues from alizarine blues; greens from Coeruleine or
Dinitrosoresorcine, etc.
Another method of mordanting cotton for the mordant group of dye-stuffs
is that in which the cotton is impregnated with a salt of the mordant
oxide derived from a volatile acid such as acetic acid, and then
subjected to heat or steaming. This method is largely taken advantage of
by calico printers for grounds, and dyers might make use of it to a much
larger extent than they do.
There are used in this process the acetates of iron, chromium and
aluminium, and bisulphites of the same metals and a few other compounds.
Baths of these are prepared, and the cotton is impregnated by steeping
in the usual way; then it is gently wrung out and aged, that is, hung up
in a warm room overnight. During this time the mordant penetrates more
thoroughly into the substance of the fabric, while the acid, being more
or less volatile, passes off--probably not entirely, but at any rate
some of the metal is left in the condition of oxide and the bulk of it
as a basic salt. Instead of ageing the cotton may be subjected to a
process of steaming with the same results. After this the cotton is
ready for dyeing, which is done by the method described in the last
section.
There is still another method to be noticed here, that is, one in which
a bath is prepared containing both the mordant and the dye-stuff. In
this case the character of the mordant must be such that, under the
conditions that prevail, it will not form a colour lake with the
dye-stuff. Such substances are the bisulphites, if used with the
bisulphite compounds of the dye-stuffs; the acetates, if mixed with some
acetic acid, may also be used. The process consists in preparing the
dye-bath containing both the mordant and the dye-stuff, entering the
cotton, steeping for some time, then wringing and steaming. During the
latter operation the acid combined with the mordant, being volatile,
passes away, and the colouring matter and mordant enter into combination
to form the colour lake, which is firmly fixed upon the fibre. Very good
results may be obtained by this method.
Lastly, in connection with the mordant colours, attention may be
directed to the process of using some of them, which consists in making
a solution of the dye-stuff in ammonia, impregnating the cotton with
this alkaline solution, and subjecting it to a steaming operation,
during which the alkali, being volatile, passes away, leaving the
colouring matter behind in an insoluble form. The cotton is next passed
into a weak bath of the mordant (preferably the acetates of iron,
etc.)., this being used first cold and then gradually heated up. The dye
on the fibre and the mordant combine to form the desired colour, which
is fixed on the fibre.
The chrome mordants are those which are most commonly applied by the
methods here sketched out, and with the large and increasing number of
mordant dyes available, the processes should be worth attention from the
cotton dyer.
The following recipes give fuller details than the outline sketches of
the methods given above for the use of the various dyes produced with
the mordant dyes and metallic mordants. In some cases as will be seen
other dyes may be added to produce special shades:--
_Dark Olive._--Prepare a bath from 8 lb. cutch, 4 lb. logwood extract, 7
lb. fustic extract, 2 lb. copper sulphate. Work in this for one to one
and a half hours at the boil. This bath may be kept standing, adding new
ingredients from time to time, and works best when it gets old. Then
pass into a cold bath of 3 lb. copperas for one hour, then wash and
enter into a new bath of 10 lb. salt, 6 oz. Titan blue 3 B, 6 oz. Titan
brown R, 6 oz. Titan yellow Y, work for one hour at the boil, then lift,
wash and dry.
_Brown._--Prepare a bath with 20 lb. cutch, 2 lb. copper sulphate, 4 lb.
quercitron extract. Work for one and a quarter hours at the boil, then
allow to lie for a day, when the goods are passed into a bath containing
3 lb. bichromate of potash and 1 lb. alum. Work at 150° to 160° F. in
this for a few minutes, then allow to lie for four to five hours, wash
well and dry.
_Olive._--Work for twenty minutes at 80° F. in a bath of 10 lb. fustic
extract, 5 lb. quercitron extract, 2 lb. logwood extract; heat to boil,
work for half an hour, then enter in a cold bath of 2 lb. sodium
bichromate and 5 lb. copper sulphate; work for twenty minutes, then heat
to boil; work for twenty minutes more, wash and dry.
_Pale Brown._--Treat in a hot bath of 25 lb. cutch, 1-3/4 lb. bluestone;
work for half an hour in this bath, then lift, wring, and work in a bath
of 1-3/4 lb. bichromate of potash for twenty to thirty minutes. Dye in a
bath of 2-1/4 lb. alum, 7 oz. Chrysoidin, 14 oz. Ponceau B.
_Fast Brown._--The cotton is heated in a boiling bath containing 20 lb.
cutch, 4 oz. copper sulphate for one hour, it is then treated in a bath
containing 8 oz. bichromate of potash for half an hour, then dyed in a
bath containing 2 oz. Benzo black blue, 6 oz. Benzo brown N B, 2 lb.
soap, 8 lb. salt, for one hour at the boil, washed and dried.
_Drab._--Dissolve 1/2 lb. cutch, 7 lb. bluestone, 8 lb. extract of
fustic; enter goods at 120° F., give six turns, lift and drain. Prepare
a fresh bath containing 2 lb. copperas; enter goods, give three turns,
lift, and enter fresh bath at 120°, containing 2 lb. bichromate of
potash, give four turns, drain, wash and dry.
_Coffee Brown._--For one piece, wet out in hot water, run for half an
hour upon a jigger in a bath of 6 lb. good cutch, take up and drain in a
bath of 8 lb. black iron liquor; drain, run again through each bath and
rinse well. Prepare a fresh bath with Bismarck brown, enter at 100° F.,
heat slowly to 200° F., drain, rinse and dry.
_Dark Brown Olive._--Prepare the dye-bath with 12 lb. cutch, 2 lb.
bluestone, 2-1/2 lb. alum, 10 lb. quercitron extract, 2 lb. indigo
carmine 4 lb. turmeric, 1/4 lb. Bismarck brown; boil for one and a half
hours, then lift and add 1 lb. copperas; re-enter the goods, give
another half-hour, boil, then add 1-1/2 lb. bichromate of potash, work
two hours more, then wash and dry.
_Red Drab._--Boil up 10 lb. cutch and 5 lb. sumac; enter the cotton at
140° F., work fifteen minutes and lift. Prepare a fresh bath of 4 lb.
black iron liquor; enter the cotton cold, work ten minutes and lift.
Prepare another bath with 3 lb. bichromate of potash; enter cotton at
160° F., work fifteen minutes, lift and wash. Finish in a fresh bath
containing 3 lb. logwood, 6 lb. red liquor; enter cotton at 100° F.,
work ten minutes, lift, wash and dry.
_Fawn._--Boil up 5 lb. cutch and 5 oz. bluestone, cool to 100° F.;
enter, give six turns, lift, and add 2 lb. copperas; re-enter cotton,
give four turns, lift and wring. Prepare a fresh bath with 1 lb.
bichromate of potash; enter cotton at 110° F., give five turns, lift,
wash and dry.
_Grey Slate._--Boil up 10 lb. sumac, 3 lb. fustic extract; cool down to
120° F., give eight turns, lift and wring. Prepare a fresh bath with 5
lb. copperas; enter cotton cold, give five turns, lift and wash.
_Dark Plum._--Lay down overnight in 30 lb. sumac. Next morning wring and
enter in a fresh bath of oxy-muriate of tin 20° Tw., give four turns,
lift and wash well in two waters. Boil out 40 lb. ground logwood, 10 lb.
ground fustic, cool bath down to 140° F.; enter cotton, give eight
turns, lift and add 1-1/2 gallons red liquor; re-enter yarn, give four
turns, lift, wash and dry.
_Pale Chamois._--Work the cotton seven turns in a cold bath of 3 lb.
copperas, then wring and pass into a cold bath of 3 lb. soda ash; work
well, wash and dry.
_Dark Brown Olive._--Prepare a bath of 28 lb. fustic, 3/4 lb. logwood,
18 lb. cutch, 4 lb. turmeric, 2 lb. copper sulphate, 3/4 lb. alum; work
for an hour at the boil, then sadden in a new bath of 1 lb. bichromate
of potash for half an hour, then sadden in a new bath of 1/4 lb. nitrate
of iron, working in the cold for half an hour, lift, wash and dry.
_Havana Brown._--Prepare a bath with 4 lb. cutch and 1 lb. bluestone;
work at the boil for one hour, then pass through a warm bath of 1/2 lb.
bichromate of potash, 1 lb. sulphuric acid. Wash and dye in a bath of
3/4 lb. Bismarck brown and 4 lb. alum; work for one hour at about 180°
F., wash and dry.
_Black._--Prepare a dye-bath with 20 lb. extract of logwood, 4 lb.
cutch, 5 lb. soda ash, 5 lb. copper sulphate. Heat to the boil, enter
the cotton, and work well for three hours, then lift, and allow to lie
overnight in a wet condition, wash and pass into a bath of 1 lb.
bichromate of potash for half an hour; lift, wash and dry. The dye-bath
is not exhausted, and only about one-third of the various drugs need be
added for further batches of cotton.
_Reseda Green._--Prepare a bath with 15 lb. cutch, 8 lb. turmeric; work
in this for fifteen minutes at about 150° F., then pass through a hot
bath of 2 lb. bichromate of potash for one hour, then re-enter into a
cutch bath to which has been added, 1 lb. sulphate of iron; work for one
hour, then add 2 lb. alum and work half an hour longer, rinse, wash and
dry.
_Fawn Brown._--Prepare a dye-bath with 4 lb. cutch, 2 lb. fustic
extract; work for one hour at hand heat, then lift, and pass through a
bath of 1-1/4 lb. bichromate of potash; work for a quarter of an hour,
rinse and pass into a fresh bath of 1 oz. Bismarck brown for ten
minutes, then lift, wash and dry.
_Beige._--Prepare a bath with 20 lb. sumac; enter cotton at 120° F.,
give six turns, lift and add 1/2 lb. copperas; re-enter cotton, give
four turns and wring. Prepare a fresh bath containing 2 lb. extract of
fustic, 3 oz. extract of indigo; enter cotton at 120° F., give three
turns, raise temperature to 140° F., and turn to shade, lift, wash and
dry.
_Turkey Red._--One of the most important colours dyed on cotton is that
known as Turkey red, a bright red of a bluish tone, characterised by its
great fastness to light, washing, etc. Strong alkalies turn it more
yellowish, but weak acids and alkalies have little action.
Into the history of the dyeing of Turkey red it is not intended to
enter, those who are interested in the subject should refer to old works
on dyeing; nor is it intended to speak of old methods of producing it
with the aid of madder, but rather to give some of the most modern
methods for dyeing it with alizarine.
Many processes differing somewhat in detail have been devised for dyeing
Turkey red on cotton, and it is probable that no two Turkey-red dyers
work exactly alike. It is difficult to produce the most perfect red, and
a very great deal of care in carrying out the various operations is
necessary to obtain it. This care and the number of operations makes
Turkey red an expensive colour to dye, and so shorter methods are in use
which dye a red on cotton that is cheaper, but not so brilliant or fast
as a true Turkey red.
_Process_ 1.--This process is perhaps the most elaborate of all
processes, but it yields a fine red. The process is applicable to cloth
or yarn, although naturally the machinery used will vary to suit the
different conditions of the material. Bleached yarn or cloth may be
treated, although a full bleach is not necessary, but the cloth or yarn
must be clean or well scoured, so that it is free from grease and other
impurities.
Operation 1. Boil the cotton for six to eight hours with a carbonate of
soda lye at 1° Tw. in a kier at ordinary pressure, then wash well,
wring, or, better, hydro-extract.
Operation 2. First "greening": What is called the "first green liquor"
is prepared by taking 15 lb. of gallipoli oil, 3 lb. phosphate of soda
and 15 lb. carbonate of soda, the liquor to stand at 2° Tw. Originally
this "liquor" was made with sheep dung, but this is now omitted. The
cotton is worked in this liquor, which is kept at 100° F., until it is
thoroughly impregnated, then it is taken out, squeezed and dried, or in
some cases piled overnight and then stoved.
Operation 3. Second green liquor. As before.
Operation 4. Third green liquor. As before.
Operation 5. A carbonate of soda liquor of 2° Tw. strength is prepared,
and the cotton steeped in this until it is thoroughly impregnated, then
it is wrung out and stoved. This is called "white liquor treatment".
Operation 6. Second white liquor. As before.
Operation 7. Steeping: Prepare a bath of water at 150° F., and steep for
twelve hours, then wring and dry.
Operation 8. Sumacing: A liquor is made from 12 lb. sumac with water,
and after straining from undissolved sumac leaves the liquor is made to
stand at 2° Tw., this is kept at about a 100° F., and the cotton is well
worked in it and allowed to steep for four hours, after which it is
taken out and wrung.
Operation 9. Mordanting or aluming: 20 lb. of alum are dissolved in hot
water, and 5 lb. of soda crystals are slowly added in order to prepare a
basic alum solution; this is now made by the addition of water to stand
at 8° Tw.
The sumaced cotton is worked in this bath and allowed to steep for
twenty-four hours, when it is taken out and wrung. Some dyers add a
little tin crystals to this bath; others add a small quantity of red
liquor.
Operation 10. The dyeing: A cold bath is prepared with 10 lb. to 12 lb.
alizarine, 3 lb. sumac extract, and 2 oz. lime. The cotton is entered
into the cold bath, worked from fifteen to twenty minutes so as to get
it thoroughly impregnated; then the heat is slowly raised to the boil
and the dyeing carried on at that heat until the full shade is obtained,
which usually takes about an hour. According to the brand of alizarine
used so will the shade that is obtained vary, as will be mentioned later
on.
Operation 11. First clearing: The dyed cotton is placed in a boiler and
boiled for four hours with 3 lb. soda crystals and 3 lb. palm oil soap,
afterwards washing well.
Operation 12. Second clearing: The dyed cotton is again boiled for two
hours with 2-1/2 lb. soap and 1/2 lb. tin crystals, then give a good
washing and dry.
This process is a long one--indeed, some dyers by repeating some of the
operations lengthen it--and it takes at least two weeks, in some cases
three weeks, to carry out.
The first idea is to get the cotton thoroughly impregnated with the oil,
and this oxidised to some extent on the fibre, and to this end the oil
treatments are carried out. In this process experience has shown that
olive oil is the best to use, although other oils have been tried from
time to time. The sumacing enables the alumina to be more firmly fixed
on to the cotton. The alumina combines with both the oil and the sumac,
and the resulting mordant produces a better and more brilliant red with
the alizarine. The clearing operations serve to remove impurities, to
brighten the colour, and to more fully fix it on the cotton.
_Process_ 2.--Operation 1. The cotton is well bleached or scoured with
soda in the usual way.
Operation 2. Oiling or preparing: A liquor is made from 10 lb. alizarine
oil or Turkey-red oil in 10 gallons water. This oil is prepared from
castor oil by a process of treatment with sulphuric acid, washing with
water and neutralising with caustic soda. The cotton is thoroughly
impregnated with this oil by steeping, then it is wrung out and dried.
Operation 3. Steaming: The cotton is put into a steaming cottage or
continuous steaming chamber and steamed for from one to one and a half
hours at about 5 lb. pressure.
Operation 4. A bath of red liquor (acetate of alumina) at 8° Tw. is
prepared. Some dyers use basic alum at the same strength. In this bath
the cotton is steeped at 100° F. for two hours; then it is wrung out and
dried. This aluming bath can be repeated. Next it is run through a bath
of chalk and water containing 2 lb. chalk in 10 gallons water. This
helps to fix the alumina on the cotton. Phosphate of soda also makes a
good fixing agent.
Operation 5. Dyeing: This is carried out in precisely the same way as in
the other process.
Operation 6. Oiling: A second oiling is now given in a bath of 5 lb.
alizarine oil, or Turkey-red oil, in 10 gallons water, after which the
cotton is dried, when it is ready for further treatment. In place of
giving a second oiling after the dyeing, it is, perhaps, better to give
it after the mordanting and before dyeing.
Operation 7. Clearing: The dyed cotton is cleared with soap in the same
manner as the clearing operations of the first process, which see.
Any of the treatments preparatory to, and following the actual dyeing
of, any of these processes may be repeated if deemed necessary. The
text-books on dyeing and the technical journals devoted to the subject
frequently contain accounts of methods of dyeing Turkey red, but when
these come to be dissected the methods are but little more than variants
of those which have just been given.
Seeing that the theory or theories involved in this rather complex
process of dyeing Turkey red, and that colourists are not agreed as to
the real part played by the oil, the sumac and the clearing operations
in the formation of a Turkey red on cotton, nothing will be said here as
to the theory of Turkey-red dyeing.
_Alizarine Red._--It is possible to dye a red with alizarine on cotton
which, while being a good colour, is not quite so fast to washing, etc.,
as a Turkey red. This is done by using fewer treatments, as shown in the
following process:--
_Process_ 1.--Boil the cotton in soda.
_Process_ 2.--Oil with Turkey-red oil, as in the Turkey-red process
No. 2 above.
_Process_ 3.--Mordant with alum or acetate of alumina.
_Process_ 4.--Dye with alizarine as before.
_Process_ 5.--Soap.
There are three distinct colouring matters which are sold commercially
under the name of "alizarine". These are: alizarine itself, which
produces a bluish shade of red; anthra-purpurine, which gives a similar
but less blue red than alizarine; and flavo-purpurine, which produces
the yellowest reds. The makers send out all these various products under
various marks.
For dyeing Turkey reds the flavo-and anthra-purpurine brands or yellow
alizarines are to be preferred; for pinks and rose shades the alizarine
or blue shade brands are best.
_Alizarine Pink._--This can be dyed in the same way as Turkey red, only
using for full pinks 4 per cent, of alizarine in the dye-bath, or for
pale pinks 1 to 2 per cent. It is advisable to reduce the strength of
the oiling and mordanting baths down to one-half.
_Alizarine Violet._--Alizarine has the property of combining with iron
to form a dark violet colour, and advantage is taken of this fact to dye
what are called in the dyeing and calico printing trades alizarine
purples and lilacs, although these do not resemble in hue or brilliance
the purples and lilacs which can be got from the direct dyes. They have
not the importance which they formerly possessed, and but a mere outline
of two processes for their production will be given.
_Alizarine Purple._--_Process_ 1. (1) Boil with soda, (2) prepare with
Turkey red oil, (3) mordant by steeping in copperas liquor at 4° Tw. for
twenty minutes, take out, allow to lie on stillages overnight, then wash
and dry. For deep purples it may be advisable to repeat these
treatments; for pale lilacs using them at half strength is advisable.
(4) Dye with 8 to 10 per cent. of alizarine blue shade, working as
described under Turkey red. The best results are obtained when 1 per
cent, of chalk is added to the dye-bath. (5) Soap as in red dyeing.
_Process_ 2. (1) Boil with soda, (2) oil with Turkey-red oil, (3) steep
in pyrolignite of iron (iron liquor) for one hour, then age by hanging
in the air. (4) Dye as before. (5) Soap.
Fine blacks are got if after oiling the cotton is treated with sumac or
tannic acid, then mordanted with iron and dyed with alizarine as usual.
_Chocolate Browns._--Fine fast chocolate browns can be got from
alizarine by using a mixed mordant of iron and alumina, either the
acetate or the sulphate. By varying the relative proportions various
shades can be obtained.
_Alizarine Orange_--Prepare the cotton as if for dyeing a Turkey red,
but use in the dye-bath 8 to 10 per cent. of Alizarine orange.
_Alizarine Blue_--The cotton is boiled three hours with 3 per cent.
ammonia soda at 30 lb. pressure, and then washed thoroughly. The boiled,
washed and hydro-extracted yarn is oiled with a solution containing from
1/4 lb. to 1-1/2 lb. Turkey-red oil, 50 per cent. for every gallon of
water. It is then wrung out evenly and dried for twelve hours at 150° F.
_Tannin Grounding._
The oiled and dried cotton is worked three-quarters of an hour in a vat
containing a tannin solution (1 oz. per gallon). The cotton remains in
this liquid, which is allowed to cool off for twelve hours, then it is
hydro-extracted. Sumac turns the shade somewhat greener, which is
noticed especially after bleaching, therefore tannin is given the
preference.
_Chromium Mordant._
The cotton treated with tannin and then hydro-extracted is worked cold
for one hour in a vat containing a solution of chromium chloride at 32°
Tw., and remains in this solution twelve hours. The cotton is then
hydro-extracted and washed directly; it is best to employ running water.
A special fixation does not take place. The cotton is now ready for
dyeing. The solution of chromium chloride and the tannin solution can be
used continuously, adding fresh liquor to keep the baths up to strength.
_Dyeing_--For dyeing, water free from lime must be used. Water having
not more than 2.5° hardness can be employed if it is corrected with
acetic acid, thereby converting the carbonate of lime into acetate of
lime. Very calcareous water must be freed from lime before use. The
dye-bath contains for 100 lb. cotton 15 lb. Alizarine blue paste (A R or
F, according to the shade desired), 35 lb. acetic acid (12° Tw.), 15-1/2
lb. ammonia (25 per cent.), 2-1/4 oz. tannin. The cotton is worked a
quarter of an hour in the cold; the temperature is raised slowly to a
boil, taking about one hour, and the cotton is worked three-quarters of
an hour at that heat. Finally the cotton is washed and hydro-extracted.
The dyed and washed cotton is steamed two hours at 15 lb. to 22 lb.
pressure. Steaming turns the shade greener and darker, and increases the
fastness. After steaming the cotton it is soaped one or two hours at the
boil, with or without pressure. According to the quality of water
employed, 2 to 5 parts soap per 1,000 parts water are taken.
_Brown._--A fine brown is got by a similar process to this, if instead
of Alizarine blue, Alizarine orange is used in the dye-bath. A deeper
brown still if Anthracene brown, or a mixture of Anthracene brown and
Alizarine blue, be used.
_Claret Red._--Clarets to maroon shade of red are got by preparing the
cotton as for blue given above, then dyeing with alizarine.
_Logwood Black._--One of the most important colours that come under this
section is logwood black, the formation of which on the fibre depends
upon the fact that the colouring principle of logwood forms a black
colour lake with iron and also one with chromium.
There are many ways of dyeing logwood blacks on cotton, whether that be
in form of hanks of yarns, warps or pieces. While these blacks may be,
and in the case of hanks are, dyed by what may be termed an intermittent
process, yet for warps and piece goods a continuous process is preferred
by dyers. Examples of both methods will be given. As in the dyeing of
Turkey reds it is probable that no two dyers of logwood blacks quite
agree in the details of their process, there may be variations in the
order of the various baths and in their relative strengths. Typical
methods will be noted here.
=Dyeing Logwood Black on Yarn in Hanks.=--Operation 1. Sumacing: Prepare
a bath with 10 lb. sumac extract in hot water. Work the yarn in this for
half an hour, then allow to steep for six hours or overnight, lift and
wring. The liquor which is left may be used again for another lot of
yarn by adding 5 lb. sumac extract for each successive lot of yarn. In
place of using sumac the cheaper myrabolam extract may be used.
Operation 2. Ironing or Saddening: Prepare a bath with 3-1/2 gallons
nitrate of iron, 80° Tw. Work the yarn in this for fifteen minutes, then
wring out. The bath may be used again when 1 gallon of nitrate of iron
is added for each lot of yarn worked in it. In place of the nitrate of
iron, the pyrolignite of iron or iron liquor may be used.
Operation 3. Liming: Work for ten minutes in a weak bath of milk of
lime.
Operation 4. Dyeing: This is done in a bath made from 10 lb. logwood
extract and 1 lb. fustic extract. The yarn is entered into the cold or
tepid bath, the heat slowly raised to about 150° F, then kept at this
heat until a good black is got, when the yarn is taken out, rinsed and
wrung. The addition of the fustic extract enables a much deeper and
jetter shade of black to be dyed.
Operation 5. Saddening: To obtain a fuller black the dyed cotton is sent
through a bath of 1-1/2 lb. of copperas, then washed well.
Operation 6. Soaping: Work for twenty minutes in a bath of 2 lb. soap at
140° to 150° F. Then wash well.
Much the same process may be followed for dyeing logwood black on warps
and piece goods, jiggers being used for each operation.
Another method is to first work the cotton in pyrolignite (iron liquor)
at 10° Tw., until it is thoroughly impregnated, then to dry and hang in
the air for some hours, next to pass through lime water to fix the iron,
and then to dye as before.
_Continuous Process._--In this case a continuous dyeing machine is
provided, fitted with five to six compartments. The cotton is first of
all prepared by steeping in a bath of 12 lb. myrabolam extract for
several hours, then it is taken to the continuous machine and run in
succession through nitrate of iron liquor, lime water, logwood and
fustic, iron liquor and water. The nitrate of iron bath contains 2
gallons of the nitrate to 10 gallons of water, and as the pieces go
through fresh additions of this liquor are made from time to time to
keep up the volume and strength of the liquor to the original points.
The logwood bath is made from 10 lb. logwood extract and 1 lb. fustic
extract, and it is used at about 160° F. The quantities here given will
serve for 100 lb. of cotton, and it is well to add them dissolved up in
hot water in small quantities from time to time as the cotton goes
through the bath.
The iron liquor given after the dyeing contains 2 lb. of copperas in 10
gallons of water.
Between the various compartments of the machine is fitted squeezing
rollers to press out any surplus liquor, which is run back into the
compartment. The rate of running the warp or pieces through should not
be too rapid, and the dyer must adapt the rate to the speed with which
the cloth dyes up in the dye-bath.
The addition of a little red liquor (alumina acetate) to the iron bath
is sometimes made, this is advantageous, as it results in the production
of a finer black. Iron by itself tends to give a rusty-looking, or
brownish black, but the violet, or lilac shade that alumina gives with
logwood, tones the black and makes it look more pleasant.
Some dyers add a small quantity, 1 per cent., of the weight of the
cotton of sulphate of copper to the iron bath, others add even more than
this. Some use nitrate of copper; the copper giving a greenish shade of
black with logwood, and this tones down the iron black and makes it more
bloomy in appearance.
Single bath methods of dyeing logwood blacks are in use, such methods
are not economical as a large quantity, both of dye-wood and mordants,
remain in the bath unused. Although full intense blacks can be dyed with
them, the black is rather loosely fixed and tends to rub off. This is
because as both the dye-stuff and the mordant are in the same bath
together they tend to enter into combination and form a colour lake that
precipitates out in the dye-bath, causing the loss of material alluded
to above, while some of it gets mechanically fixed on the cotton, in a
more or less loose form, and this looseness causes the colour to rub
off.
For a _chrome-logwood black_, a dye-bath is made with 3 lb. bichromate
of potash, 100 gallons logwood decoction at 3° Tw., and 6-1/2 lb.
hydrochloric acid. Enter the cotton into the cold bath, raise slowly to
the boil and work until the cotton has acquired a full black blue
colour, then take it out and rinse in a hot lime water when a blue black
will be got.
A _copper-logwood black_ is got by taking 100 gallons logwood decoction
at 3° Tw., and 6 lb. copper acetate (verdigris); the cotton is entered
cold and brought up to the boil. Copper nitrate may be used in the place
of the copper acetate, when it is a good plan to add a little soda to
the bath. Some dyers in working a copper-logwood black make the dye-bath
from 100 gallons logwood liquor at 2° Tw., 4 lb. copper sulphate
(bluestone) and 4 lb. soda. This bath is used at about 180° to 190° F.,
for three-quarters of an hour, then the cotton is lifted out, wrung and
aged or as it is sometimes called "smothered" for five hours. The
operations are repeated two or three times to develop a full black.
Logwood black dyeing has lost much of its importance of late years owing
to the introduction of the many direct blacks, which are much easier of
application and leave the cotton with a fuller and softer feel.
_Logwood Greys._--These are much dyed on cotton and are nothing more
than weak logwood blacks, and may be dyed by the same processes only
using baths of about one-tenth the strength.
By a one-bath process 5 lb. of logwood are made into a decoction and to
this 1 lb. of copperas (ferrous sulphate) is added and the cotton is
dyed at about 150° F. in this bath. By adding to the dye-bath small
quantities of other dye-woods, fustic, peach wood, sumach, etc., greys
of various shades are obtained. Some recipes bearing on this point are
given in this section.
Logwood is not only used for dyeing blacks and greys as the principal
colouring matter, but is also used as a shading colour along with cutch,
fustic, quercitron, etc., in dyeing olives, browns, etc., and among the
recipes given in this section examples of its use in this direction will
be found.
The dye-woods--fustic, Brazil wood, bar wood, Lima wood, cam wood,
cutch, peach wood, quercitron bark, Persian berries--have since the
introduction of the direct dyes lost much of their importance and are
now little used. Cutch is used in the dyeing of browns and several
recipes have already been given. Their production consists essentially
in treating the cotton in a bath of cutch, either alone or for the
purpose of shading with other dye-woods when the cotton takes up the
tannin and colouring matter of the cutch, etc. The colour is then
developed by treatment with bichromate of potash, either with or without
the addition of an iron salt to darken the shade of brown.
The usual methods of applying all the other dye-woods, to obtain
scarlets to reds with Brazil wood, Lima wood, peach wood; or yellows
with fustic, quercitron or Persian berries, is to first prepare the
cotton with sumac, then mordant with alumina acetate or tin crystals
(the latter gives the brightest shades), then dye in a decoction of the
dye-woods. Sometimes the cotton is boiled in a bath of the wood when it
takes up some of the dye-wood, next there is added alumina acetate or
tin crystals and the dyeing is continued when the colour becomes
developed and fixed upon the cotton.
Iron may be used as a mordant for any of these dye-woods but it gives
dull sad shades.
Chrome mordants can also be used and these produce darker shades than
tin or alumina mordants.
As practically all these dye-woods are now not used by themselves it has
not been deemed necessary to give specific recipes for their
application, on previous pages several are given showing their use in
combination with other dyes.
The dye-stuff Dinitroso-resorcine or Solid green O is used along with
iron mordants for producing fast greens and with chrome mordants for
producing browns to a limited extent in cotton dyeing. The following
recipes give the details of the process.
_Green._--Steep the cotton yarn or cloth in the following liquor until
well impregnated, then dry: 3 gallons iron liquor (pyrolignite of iron),
22° Tw. gallons of water, 3/4 gallon acetic acid, 12° Tw., 2 lb.
ammonium chloride. Then pass the cotton through a warm bath of 3 oz.
phosphate of soda and 4 oz. chalk per gallon, then enter into a dye-bath
containing 6 lb. Solid green O. Work as described for dyeing alizarine
red. For darker greens of a Russian green shade use 10 lb. of solid
green O, in the dye-bath.
_Brown._--A fine brown is got by steeping the cotton in a bath of 8 lb.
Solid green O, 6-3/4 gallons water, 1-1/2 gallons ammonia and 2 lb.
acetate of chrome; dry, then pass through a soap-bath, wash and dry.
_Deep Olive Brown._--Mix 8 lb. Solid green O and 4-1/2 lb. borax with 6
gallons water, add 1/2 lb. Turkey-red oil, 5 lb. ammonia, then 2 gallons
water and 1-1/2 lb. copper-soda solution and another 2 gallons water.
Steep the cotton in this, dry, soap well and wash. The copper-soda
solution is made from 10 lb. chloride of copper (75° Tw.), 5 lb.
tartaric acid, 12 lb. caustic soda (75° Tw.) and 4 lb. glycerine.
_Khaki._--Make the dye liquor from 14 lb. Solid green O, 1/2 lb.
Alizarine yellow N, 1 lb. caustic soda (36° Tw.), 1/2 lb. Turkey-red oil
and 8 gallons water. To this add 2-1/2 lb. acetate of chrome (32° Tw.),
2-1/4 lb. copper-soda solution and 4 gallons water.
_Sage Green._--Use 1-1/4 lb. Solid green O, 3 lb. caustic soda (36°
Tw.), 1/2 lb. Ceruleine, 1/2 lb. Turkey-red oil, 1 gallon water to which
is added 2-1/2 lb. acetate of chrome (32° Tw.) and 2-1/4 lb. copper-soda
solution dissolved in 4 gallons water.
_Pale Brown._--Use 4 lb. Solid green O, 2-1/2 lb. borax, 3 lb. ammonia,
1/2 lb. Turkey-red oil, 6 gallons of water and 1-1/2 lb. copper-soda
solution dissolved in 2 gallons water.
_Pale Fawn Brown._--The dye-bath is made from 1/2 lb. Alizarine, 1-1/4
lb. Solid green O, 1-1/2 lb. borax, 1/2 lb. Turkey-red oil and 5 gallons
of water to which is added 1-1/2 lb. acetate of chrome (32° Tw.), 1-1/2
lb. copper-soda solution and 4 gallons water. In all cases the cotton is
steeped in the dye liquors until thoroughly impregnated, then the excess
liquor is wrung out, the cotton dried, then passed through a soap bath,
washed well and dried.
_Dark Brown._--Place the cotton in a lukewarm bath of 25 lb. cutch and
1-1/2 lb. copper sulphate; work for half an hour, then steep for six
hours, then lift, wring and enter into a bath of 3-1/4 lb. bichromate of
potash at 160° F. for twenty minutes. Then wash and dry.
_Yellow Brown._--Make a bath with 14 lb. cutch and 1/2 lb. copper
sulphate; work in this bath for four hours at 120° F., then pass into a
bath of 2 lb. copperas and 1/2 lb. chalk, work for half an hour in the
cold, then pass into a hot bath of 2-1/2 lb. bichromate of potash at
150° F. for half an hour.
_Dark Brown._--Make a dye-bath with 15 lb. cutch, 2 lb. logwood extract
and 2 lb. fustic extract; work the cotton in this at 160° F. for three
hours, then pass into a cold bath of 1 lb. copperas and 1/4 lb. chalk
for half an hour, then into a bath of 3 lb. bichromate of potash for
half an hour at 150° F., then wash and dry.
(7) PRODUCTION OF COLOUR DIRECT UPON COTTON FIBRES.
By the action of nitrous acid upon the salts of the primary organic
amines the so-called diazo compounds are formed. An example of this
important process is that of nitrous acid on aniline hydrochloride shown
in the following equation:--
C{6}H{5}NH{2} + HCl + HNO{2} 2H{2}O + C{6}H{5}N:NCl
Hydrochloric acid Nitrous Water, Diazo-benzene
aniline, acid, chloride.
These diazo compounds are distinguished by their active properties,
especially in combining with amines in acid solutions, or with phenols
in alkaline solution to form the azo dyes, thus diazobenzene chloride
will combine with naphthol to form naphthol-azo-benzene, thus:--
C{6}H{5}N:NCl + C{10}H{7}OH + NaOH =
Diazo-benzene chloride, Naphthol, Caustic soda.
C{10}H{6}OHN:NC{6}H{5} + NaCl + H{2}O
Naphthol-azo-benzene, Salt, Water.
These azo compounds are coloured, but are perfectly insoluble in water,
alkalies, or acids; on the other hand the sulphonates of these bodies
are easily soluble and form the numerous azo dyes now so largely made
and used in wool and silk dyeing, but which on account of their being
sulphonates cannot be used for cotton dyeing.
Methods have been devised for producing the insoluble azo colours direct
upon the fibres. They are also called naphthol colours from the use of
beta-and alpha-naphthol in their production. Although these azo dyes,
when produced on the fibre, do not possess the fastness of the alizarine
dyes, yet, on account of their cheapness and relative great fastness to
soap and the action of sunlight, they are better than many of the newer
cotton dyes.
By this method (first introduced in England by Holliday) colours of
exceptional brightness and fastness can be obtained which were not
obtainable with the dyes then known. Those which are obtained from
phenols are of the first importance.
_The Diazotisation of the Amido Bases._
With most bases this must be accomplished as cold as possible below 65°
F. At a higher temperature, and when allowed to stand, most diazo
compounds decompose quickly with evolution of nitrogen, which
decomposition results in the mixture losing its power of producing
colour, or at the most gives unsatisfactory results. For this reason it
is therefore always necessary to work as cold and as quickly as
possible.
The amido-azo bodies, whose compounds with the phenols are also
distinguished by their great fastness, are in this respect an exception.
They can be diazotised at the ordinary temperature, and their diazo
compounds are much stabler than those, for example, of alpha-and
beta-naphthylamine or of aniline, which must always be used as quickly
as possible.
From anisidine, phenetidine and amido-diphenylamine, still more stable
diazo compounds can be obtained, but the prices of these bases are
rather high, and the colours produced with them are not fast to light.
The cheapest and most convenient method of obtaining nitrous acid for
diazotising is by the action of a mineral acid, preferably hydrochloric
acid, upon nitrite of soda.
For diazotising one molecule of base requires one molecule of
hydrochloric acid to form a salt of the base, a molecule of nitrite of
soda, and another molecule of hydrochloric acid to decompose the
nitrite. The diazotisation is better carried out and the diazo solution
rendered more stable if another molecule of hydrochloric acid and an
excess of nitrite of soda are used. The presence of an excess of nitrite
can be determined by testing the diazo solution with potassium iodide
starch paper, which in the presence of excess of nitrite gives the blue
iodine starch reaction.
In carrying out the diazotisation, the base is first dissolved in the
whole amount of hydrochloric acid which has to be used, and the solution
is filtered. The diazotisation takes place in the manner shown in the
equation:--
C{6}H{5}NH{2} + HCl + HCl + NaNO{2} =
Aniline hydrochloride, Hydrochloric acid, Sodium nitrite,
NaCl + C{6}H{5}N:NCl + H{2}0
Salt, Diazo-benzene chloride, Water.
The bases which form salts soluble with difficulty, such as nitroaniline
and the amido-azo bodies, offer special difficulties in diazotising.
It has been found that the operation with these is best carried out if
the chemically pure bases in paste form are mixed with the requisite
amount of nitrite, and the diluted paste then poured into the
hydrochloric acid.
It has been found by experience that the colour is developed much
brighter upon the fibre when the diazo solution contains acetic acid and
no free mineral acid. However, the diazotisation is better carried out
with hydrochloric acid, and the presence of the latter is necessary to
give stability to the solution. If before the diazo solution is used a
quantity of acetate of soda be added to it, the free hydrochloric acid
liberates acetic acid from the acetate, and the chloride of the diazo
body changes into its acetate. It is better to add an excess above the
two molecules of acetate of soda which are required.
The combination when aniline and beta-naphthol are used, as the amine
and phenol respectively, is shown in the following equations:--
C{6}H{5}N:NCl + C{10}H{7}OH +
Diazo-benzene chloride, B. naphthol,
NaOH = 2NaCl + C{6}H{5}N:NC{10}H{6}OH + H{2}O
Caustic soda, Benzene- azo-naphthol, Water.
Or, with naphthylamine and naphthol, thus:--
C{10}H{7}N:NCl + C{10}H{7}OH + NaOH =
NaCl + C{10}H{7}N:NC{10}H{6}OH + H{2}O
Naphthalene azo-naphthol.
By the action of nitrous acid upon amido-azo bodies a group of bodies
called diazo-azo compounds are obtained which contain the group N:N
twice over, thus:--
C{6}H{5}N:NC{6}H{4}NH{2}HCl + NaNO{2} + 2HCl =
Benzene-azo-aniline-hydrochloride,
NaCl + C{6}H{5}N:NC{6}H{4}N:NCl + 2H{2}O.
Diazo-azo-benzene-chloride.
When this compound is combined with naphthol diazo-azo dyes are
produced.
C{6}H{5}N:NC{6}H{4}N:NC{10}H{6}OH.
Benzene-azo-benzene-azo-naphthol.
The molecular weights of the bases, phenols and chemicals employed are
the following:--
1. Hydrochloric acid, HCl--36.5. 2. Caustic soda, NaOH--40. 3. Nitrite
of soda, NaNO{2}--69. 4. Acetate of soda, NaC{2}H{3}O{2}3H{2}O--136.
1. Commercial hydrochloric acid at 32° Tw. contains about 365 grams of
HCl in a litre, or 3-1/2 lb. in a gallon.
2. The commercial 77 per cent. soda must always be used, and for
practical purposes it may be taken as pure. It is best to make a
solution which contains 160 grams NaOH in a litre of water.
3. The nitrite supplied is almost chemically pure, and is easily soluble
in water. In order to make a solution 140 or 290 grams are dissolved per
litre.
4. Crystallised acetate of soda contains 3 molecules of water of
crystallisation, and is usually somewhat moist. Instead of 136 grams 140
are taken to allow for moisture. The amount is dissolved in about 500
cubic centimetres of water.
_Bases._
1. Aniline, C{6}H{5}NH{2}--93.
2. Toluidine, C{7}H{7}NH{2}--107.
3. Alpha-and beta-naphthylamine, C{10}H{7}NH{2}--143.
4. Para-or meta-nitroaniline, C{6}H{4}NO{2}NH{2}--138.
5. Nitro-para-toluidine, C{7}H{6}NO{2}NH{2}--152.
6. Amidoazobenzene (base), C{6}H{5}N:NC{6}H{4}NH{2}--197.
7. Orthoamidoazotoluol (base), C{7}H{7}N:NC{7}H{6}NH{2}--225.
8. Alpha-or beta-naphthol C{10}H{7}OH--144.
_Example of Quantities Taken._
Molecular Weight.
1. Molecule nitrite 69 grams.
2. Molecule aniline 93 "
3. Molecule hydrochloric acid 365 "
4. Molecule acetate of soda 136 "
5. Molecule of naphthol 144 "
6. Molecule caustic soda 40 "
Applying the principles which have just been described to the dyeing of
cotton, it is found that the cotton may be dyed by taking the base and
preparing the diazo body, impregnating the cotton with this, and
developing the colour by passing into a bath of the phenol. On the other
hand, the cotton can be prepared with the phenol and the colour
developed by passing into a bath of the diazotised base, and practice
has shown that this latter proceeding is the best. Practically the only
phenol that is used is the beta-naphthol; alpha-naphthol is occasionally
used, but not often.
The purer the beta-naphthol the better, especially for producing the
paranitroaniline red. Various preparations of beta-naphthol have been
brought out by colour makers.
The process of dyeing cotton with a naphthol colour takes place in two
stages, the first being the grounding or preparing with the naphthol,
the second the developing with the diazotised base. Some of the effects
which can be obtained from the two naphthols and various bases are given
in the following table:--
Base. With beta-naphthol, gives With alpha-naphthol, gives
1. Aniline, Orange yellow; Cutch brown.
2. Paratoluidine, Full yellow orange; Cutch brown.
3. Metanitroaniline, Fiery yellowish red; Brownish orange.
4. Paranitroaniline, Bright scarlet; " "
5. Nitroparatoluidine, Orange; Very bright catechu.
6. Alpha-naphthylamine, Bluish claret red; Reddish puce.
7. Beta-naphthylamine, Turkey red; "
8. Amidoazobenzene, Red; "
9. Orthoamidoazotoluene, Yellowish claret red; "
By mixing alpha-and beta-naphthols together a variety of grenat and
claret reds and browns can be obtained.
With regard to the fastness of the shades produced the following may be
considered:--
_Fast to Soaping._
Combination of A-Naphthol with Toluidine.
" " A-Naphthylamine.
" " B-Naphthylamine.
" " Amidoazobenzene.
" B-Naphthol with Toluidine.
" " Paranitroaniline.
" " Nitroparatoluidine.
" " B-Naphthylamine.
" " A-Naphthylamine.
_Moderately Fast._
Combination of A-Naphthol with Aniline.
" " Paranitroaniline.
" " Orthoamidoazotoluene.
" B-Naphthol with Metanitroaniline.
" " Amidoazobenzene.
_Very Loose._
Combination of A-Naphthol with Paratoluidine.
" " Metanitroaniline.
" " Nitroparatoluidine.
" B-Naphthol with Aniline.
" " Paratoluidine.
" " Orthoamidoazotoluene.
The samples were tested for fastness to light by exposing them for nine
days with the following results:--
_Fast._
Combination of A-Naphthol with Aniline.
" " Toluidine.
" " Metanitroaniline.
" " Paranitroaniline.
" " Nitroparatoluidine.
" " B-Naphthylamine.
" " Amidoazobenzol.
" " Orthoamidoazotoluol.
" B-Naphthol with Aniline.
" " Paratoluidine.
" " Metanitroaniline.
" " Paranitroaniline.
" " B-Naphthylamine.
" " A-Naphthylamine.
_Moderately Fast._
Combination of B- Naphthol with Nitroparatoluidine.
_Very Loose._
Combination of A-Naphthol with Toluidine.
" " A-Naphthylamine
" B-Naphthol with Toluidine.
" " Amidoazobenzene.
" " Orthoamidoazotoluene.
The most important of the naphthol colours is undoubtedly
paranitroaniline red, produced by the combination of paranitroaniline
and beta-naphthol. In order to produce the best and brightest shades
these two bodies must be quite pure. The following directions may be
followed:--
=Dyeing Paranitroaniline Red on Yarn.=
It unfortunately happens that this red does not admit of being worked in
large quantities at a time, particularly in the diazo bath where the
colour is developed, as the previous operations seem to render the yarn
slightly waterproof, and hence if large quantities of yarn were dealt
with at one time some would be found to be dyed all right, others would
be defective. It has, therefore, been found best to work only about 2
lb. of yarn at a time, carefully carrying out each operation with this
quantity. As, however, the process can be quickly worked it follows that
in the course of a day a fairly large quantity of yarn can be treated.
1. _Grounding._ The grounding or preparing bath for 100 lb. of yarn is
best made in the following manner: 4 lb. of beta-naphthol are stirred in
2-1/2 lb. of caustic soda liquor 70° Tw., then 1-1/2 quarts of boiling
water is added, when dissolved 1-1/2 quarts of cold water. In a separate
vessel dissolve 5 lb. Turkey-red oil in 11 quarts of water, then mix the
two liquors together and add sufficient water to make up the whole to 12
gallons.
In working sufficient of this liquor is taken and put into a deep tub in
which 2 lb. of yarn can be conveniently worked. It is best to work at a
tepid heat, say 100° to 110° F.; 2 lb. of the yarn are worked in this
liquor, so that it becomes thoroughly impregnated, then it is gently
wrung out and hung up. This operation is repeated with each 2 lb. until
the whole 100 lb. has been treated, adding from time to time some of the
naphthol liquor to make up for that taken up by the cotton. When all the
yarn has been through the liquor, give it another dip through the same
liquor. Place the yarn in a hydro-extractor for five to seven minutes.
Next open out the yarn well, and hang on sticks and dry in a stove at
140° to 150° F. The stove should be heated with iron pipes, through
which steam at 30 lb. to 40 lb. pressure passes. This stove should be
reserved entirely for this work, for if other goods be dried in it along
with the naphthol-prepared cotton, any steam or acid vapours which might
be given off from the former might damage the latter.
When thoroughly dry the yarn is ready for the next operation.
2. _Developing._ The developing bath is made in the following manner:
1-1/2 lb. paranitroaniline is mixed with 1-1/2 gallons of boiling water,
and 1-3/4 quarts of hydrochloric acid at 30° to 32° Tw. Stir well until
the paranitroaniline is completely dissolved, add 3-1/2 gallons of cold
water, which will cause a precipitation of the hydrochlorate of
paranitroaniline as a yellow powder. Let the mixture thoroughly cool
off, best by allowing to stand all night; 1-1/4 lb. of nitrite of soda
is dissolved in 4 quarts of cold water, and this solution is added to
the paranitroaniline solution slowly and with constant stirring; in
about fifteen to twenty minutes the diazotisation will be complete. At
this and following stages the temperature of working should be kept as
low as possible. Some dyers use ice in preparing their diazo solutions,
and certainly the best results are attained thereby, but with
paranitroaniline the ice can be dispensed with. After the end of the
time sufficient cold water is added to bring the volume of the liquor up
to 10 gallons. This diazo liquor will keep for some days, but it
decomposes in time, so that it should not be kept too long.
Another liquor is made by dissolving 4 lb. acetate of soda in 11 quarts
of water.
The developing bath is made by taking 4 gallons of the diazo liquor and
1 gallon of the acetate liquor and mixing together, and in this bath the
prepared yarn, 2 lb. at a time, is worked. The colour develops
immediately. The yarn when dyed is lifted out, wrung, and then it is
well washed with water, soaped in a bath at 120° F., with a liquor
containing 1/2 oz. soap per gallon, then dried. As the cotton yarn is
being passed through the developing bath, the latter is freshened up
from time to time by suitable additions of the diazo and acetate liquors
in the proportions given above.
Some dyers use a special form of dye vat for dyeing paranitroaniline red
on yarn, whose construction can be seen from Fig. 27.
[Illustration: FIG. 27.--Dye-tub for Paranitroaniline Red.]
The beta-naphthol bath does not keep well and in time tends to grow
brown, and when this occurs stains are invariably produced on the
cotton. When the yarn or cloth has been prepared with the beta-naphthol,
and dried, the developing should be immediately proceeded with, for it
is found that by allowing the prepared cotton to lie about it becomes
covered with brown stains, and when such stained cotton is passed
through the developing bath stains and defective dyeing result.
It has been found that by adding a little tartar emetic to the
beta-naphthol bath this is largely if not entirely prevented, and the
prepared cloth may be kept for a reasonable length of time before
proceeding with the development without fear of stains being formed.
Various additions have been made from time to time to the naphthol bath.
Some of these take the form of special preparations of the colour
manufacturers, and are sold as naphthol D, naphthol X, red developer C,
etc., sometimes gum tragacanth has been added, at others in place of
Turkey-red oil there is used a soap made from castor oil with soda and
ammonia, but such complicated baths do not yield any better results than
the simple preparing liquor given above.
[Illustration: FIG. 28.--Padding Machine for Paranitroaniline Red.]
=Dyeing Paranitroaniline Red on Piece Goods.=
The dyeing of this red on to piece goods only differs from that on yarn
by reason of the difference in the form of material that is dealt with.
1. _Preparing or Grounding._--The same liquor may be used. This
operation is best done on a padding machine, a sketch of which is given
in Fig. 26, showing the course of the cloth through the liquor. This is
contained in the box of the machine, and this is kept full by a constant
stream flowing in from a store vat placed beside the machine. After
going through the liquor, the cloth passes between a pair of squeezing
rollers which squeeze out the surplus liquor. Fig. 28 shows a view of a
padding machine adapted for grounding paranitroaniline reds. After the
padding, the cloth is dried by being sent over a set of drying
cylinders, or through what is known as the hot flue.
2. _The Developing._--After being dried, the pieces are sent through a
padding machine charged with the developing liquor made as described
above, after which the cloth is rinsed, then soaped, and then washed.
Some dyers use a continuous machine for these operations, such as shown
in Fig. 29.
While the developing bath used for piece goods may be the same as that
used for yarns, some dyers prefer to use one made somewhat differently,
thus 6-1/4 lb. paranitroaniline are mixed with 7 gallons boiling-water
and 1-1/2 gallons hydrochloric acid; when dissolved 16 gallons of cold
water are added, then, after completely cooling, 3-1/2 lb. sodium
nitrite dissolved in 3 gallons cold water. After twenty minutes, when
the diazotisation is complete, water is added to make the whole up to 40
gallons. The acetate liquor is made from 13-1/4 lb. acetate of soda in
13-1/2 gallons of water.
Equal quantities of these two liquors are used in making the developing
bath.
[Illustration: FIG. 29--Developing Machine for Paranitroaniline Red.]
Of late years, under the names of Azophor red P N, Nitrazol C,
Nitrosamine, etc., there has been offered to dyers preparations of
diazotised paranitroaniline in the form of a powder or paste, readily
soluble in water, that will keep in a cool and dry place for any
reasonable length of time. These are prepared in various ways, and to
any dyer who does not want the trouble of diazotising the
paranitroaniline they offer some advantages. They produce a red equal in
every respect to that obtained from paranitroaniline. The following
details show the method to be followed with some of these products,
others are very similar to make the developing baths.
_Paranitroaniline Red with Nitrazol C._--Dissolve 25 lb. Nitrazol C in
12 gallons of cold water with constant stirring, then add sufficient
cold water to make 37 gallons. In another vessel dissolve 11 lb. of
acetate of soda in 5-1/2 gallons water, then add 1-1/2 gallons caustic
soda, 36° Tw., mixed with 5-1/2 gallons water. The developing bath is
made by mixing both these solutions. It will suffice for both yarn and
piece goods.
_Paranitroaniline Red with Azophor Red P N._--Dissolve 5-1/2 lb. of
Azophor red P N in 4 gallons of water--it dissolves almost completely
but usually a few particles of a flocculent character remain
undissolved, these can be removed; 2-1/4 gallons of caustic soda lye of
36° Tw. are diluted with water to 10 gallons, and this is added with
constant stirring to the azophor red P N solution. When all is mixed and
a clear solution obtained, the developing bath is ready for use, and is
used in the same way as the paranitroaniline bath.
_Metanitroaniline Orange._--This orange is produced in the same way as
the paranitroaniline red, using metanitroaniline or Azophor orange M N
in place of the paranitroaniline or the Azophor red P N given for the
red. The quantities of all the materials used are identical.
_Nitrosamine Red._--Dissolve 5 lb. Nitrosamine red in 5 gallons of water
and 2-1/4 lb. hydrochloric acid, when well mixed there is added 2-1/2
lb. acetate of soda, when all is dissolved add sufficient water to make
6-1/2 gallons. This bath is used exactly in the same way as the
paranitroaniline developing bath, and it produces identical results in
every way.
_Paranitroaniline Brown._--By boiling the paranitroaniline red dyed
cotton in a weak bath of copper sulphate a very fine fast brown
resembling a cutch brown is produced. A better plan, however, is to
prepare the cotton with a ground containing an alkaline solution of
copper, 3 lb. beta-naphthol are dissolved in 5 pints of caustic soda lye
of 36° Tw., to which is added 5 lb. Turkey-red oil and 10 pints alkaline
copper solution, water being added to make 13 gallons of liquor. The
cotton is treated in this way as with the ordinary beta-naphthol
preparation. The alkaline copper solution is made by taking 5 pints of
copper chloride solution at 76° Tw., adding 3-1/4 lb. tartaric acid, 6
pints caustic soda lye, 70° Tw., and 2 pints of glycerine. The
developing bath for the brown is the same as for the paranitroaniline
red, or the Azophor red P N bath may be used.
_Toluidine Orange._--For this colour the cotton is prepared with the
beta-naphthol in the ordinary way. The developing bath is made from 2
lb. orthonitrotoluidine mixed with 12 pints boiling water and 2-1/4
pints hydrochloric acid; when dissolved allow to cool and then add
12-1/2 lb. ice. When thoroughly cold stir in 2-1/2 pints of sodium
nitrite solution containing 3 lb. per gallon. Stir well for twenty
minutes, then filter; add 4 lb. sodium acetate and sufficient ice-cold
water to make 13 gallons. Use this bath in the same way as the
paranitroaniline bath.
_Beta-naphthylamine Red._--This red is a good one, but is not so bright
or so fast as the paranitroaniline red, hence although somewhat older in
point of time it is not dyed to the same extent. The developing bath is
made from 1-3/4 lb. beta-naphthylamine dissolved with the aid of 10
pints boiling water and 1 pint hydrochloric acid. When dissolved allow
to cool; add 27 lb. ice and 2 pints hydrochloric acid. When cooled to
32° to 36° Tw., add 3 pints sodium nitrite solution (3 lb. per gallon)
and 4 lb. sodium acetate, making up to 13 gallons with water. This also
is used in precisely the same way as the paranitroaniline red developing
liquor.
_Alpha-Naphthylamine Claret._--This is a very fine and fairly fast red,
and next to the paranitroaniline red may be considered the most
important of the naphthol colours. The developing bath is a little more
difficult to make, owing to the fact that it is more difficult to get
the alpha-naphthylamine into solution. The best way of proceeding is the
following: Heat 1-3/4 lb. of alpha-naphthylamine in 10 pints of boiling
water, agitating well until the base is very finely divided in the
water, then 1-1/4 pints of hydrochloric acid is added, and the heat and
stirring continued until the base is dissolved, then the mass is allowed
to cool, 27 lb. of ice is added and 1-1/2 pints of hydrochloric acid.
When cooled down to 32° to 36° F., there is added 3 pints sodium nitrite
solution (3 lb. per gallon), and after allowing the diazotisation to be
completed, 4 lb. sodium acetate and sufficient water to make 13 gallons
of liquor.
The bath is used in the same manner as the previous developing baths.
_Dianisidine Blue._--Dianisidine develops with beta-naphthol, a violet
blue, which is not very fast, but by the addition of some copper to the
developing bath a very fine blue is got which has a fair degree of
fastness. The developing bath is made as follows: Mix 10-1/2 oz.
dianisidine with 7 oz. hydrochloric acid and 7-1/2 pints of boiling
water, when complete solution is obtained it is allowed to cool, then 20
lb. of ice is added. Next 1-3/4 pints of nitrite of soda solution,
containing 1-1/2 lb. per gal. and 2-1/2 pints of cold water. Stir for
thirty minutes, then add 1-1/4 pints copper chloride solution at 72°
Tw., and sufficient water to make up 6-1/2 gallons.
The cotton is prepared with beta-naphthol in the usual way, and then
passed through this developing bath.
_Amidoazotoluol Garnet._--Amidoazotoluol produces with beta-naphthol a
fine garnet red in the usual way.
The developing bath is made from 14 oz. amidoazotoluol, mixed with 1-1/2
pints of sodium nitrite solution containing 1-1/2 lb. per gallon, when
well mixed add 1 pint of hydrochloric acid diluted with 2 pints water,
when this is well mixed add sufficient water to make up a gallon, then
add 1 lb. acetate of soda.
The cotton is passed through this dye-bath, then washed well, passed
through a weak acid bath, then soaped well, washed and dried.
(8) DYEING COTTON BY IMPREGNATION WITH DYE-STUFF SOLUTION.
Indigo is a dye-stuff which requires special processes for its
application to the cotton or wool fibre.
Its peculiarity is that in the form in which it comes to the dyer it is
insoluble in water, and to enable it to be dissolved and therefore to be
used as a dye, the indigo has to go under a special treatment. The
colouring principle of indigo is a body named indigotin, to which the
formula C{16}H{16}N{2}O{2} has been given. When indigo is mixed with
substances like lime and copperas, lime and zinc, zinc and bisulphite of
soda, which cause the evolution of nascent hydrogen, it takes up this
body and passes into another substance which is called indigo white that
has the formula C{16}H{12}N{2}O{2}, leuco, or white indigo; this
substance is soluble in water, and so when it is formed the indigo
passes into solution and can then be used for dyeing. But indigo white
is an unstable substance on exposure to air, the oxygen of the latter
attacks the hydrogen which it has taken up, and indigotin is reformed,
the indigo white changing again into indigo blue.
Indigo dyeing consists of three operations:--
(1) Preparation of the indigo solution, or, as it is called,
setting the dye vat. (2) Steeping the cotton in this vat. (3)
Exposing to the air.
[Illustration: FIG. 30.--Indigo Dye-vat for Cloth.]
There are several methods of preparing, or setting the dye vat, and of
each of these modifications are in use in every indigo dye-house:--
(1) With lime and copperas. (2) Zinc and lime vat. (3) Zinc and
bisulphite of soda.
In all cases it is necessary for the indigo to be ground to the form of
a fine paste with water; this is usually done in what is known as the
ball-grinding mill. The finer it is ground the more easy is it to make
the dye-vats.
The dye-vats may be either round tubs or square wooden tanks; when
cloths or warps are being dyed these may be fitted with winces and guide
rollers, so as to draw the materials through the liquor. In the case of
yarns in hanks these appliances are not necessary.
Fig. 30 is a sketch of an indigo dye-vat for cloth or warps.
(1) =Lime and Copperas Vat.=--To prepare this vat take 75 gallons of
water, 4 lb. of indigo, 8 lb. copperas, and 10 lb. of good quicklime.
Put these into the vat in the order shown. The amount of indigo is added
in proportion to the shade which is required to be dyed: for pale
shades, 2 lb. to 3 lb. will be sufficient; while for deep shades, 6 lb.
to 7 lb. may be used. The amount of copperas should be from one and a
half to twice that of the indigo. The vat should be stirred very well
and then left to stand. The changes which occur are probably the
following: The lime acts upon the copperas and produces ferrous
hydrate--this is unstable and tends to take up oxygen and hydrogen from
the water, particularly when there is some indigo present, and forms
ferric hydrate; hydrogen is at the same time liberated, and combines
with the indigo to form the soluble indigo white. It takes about
twenty-four hours to make an indigo vat. When properly made and in good
condition, the liquor will be clear and of a brownish-yellow colour, a
bluish scum may collect on the surface. If the liquor appears at all
greenish it is an indication that the indigo has not been completely
reduced, and the vat needs a further addition of lime and copperas,
which should be of good quality. Too much of each should not be used,
because with them there is formed at the bottom of the vat a sediment of
calcium sulphate and ferric hydrate, and it is not wise to increase this
to too great an extent, which would be the case if too much lime and
copperas were added.
_To Use this Vat._--Any scum on the surface is raked on one side, the
cotton yarn immersed for a few minutes, then it is taken out, wrung,
allowing the excess liquor to flow back into the vat, and the yarn hung
up in the air for the blue to develop. The depth of shade which is dyed
depends chiefly upon the amount of indigo in the vat, and also upon the
time during which the hanks are dipped in the liquor. Light and medium
shades can be readily and conveniently got by a single dip, but deep
shades are best got by repeating the dipping once or twice as occasion
demands. Deep shades got by using a strong bath at a single dip are
found to rub badly, while by repeated dips the dye gets more into the
substance of the fibre, and therefore the colour is more firmly fixed
and it rubs less.
Some indigo dyers have quite a range of vats, using those fresh made for
dyeing deep shades, while the old vats being nearly exhausted are used
only for light shades and finally when completely exhausted are thrown
away. After the day's work the vat should be stirred up and then allowed
to stand. If necessary it may be strengthened by the addition of fresh
quantities of indigo, lime and copperas, the next morning it will be
ready for use. Generally a lime-copperas vat will remain in good working
order for about a month, when it will be necessary to throw it away.
=(2) Zinc and Lime Vat.=--Zinc dust is a bye-product in the process of
zinc extraction. It is a grey, very heavy powder, consisting mostly of
finely divided metallic zinc, with traces of oxide and sulphide of zinc.
Of these only the metallic zinc is active in reducing the indigo, the
rest of the ingredients are not of any consequence. The valuation of
zinc dust is a very difficult operation, but it is desirable that this
be done, as the product is liable to be very variable in the proportion
of actual zinc it contains, and it will pay large buyers always to have
it tested. Zinc dust must always be kept in a dry place.
For the reduction of zinc powder lime is chiefly used. The following are
two good mixtures.
Vat with zinc and lime:--
10 lb. indigo, dry and ground fine;
5-1/2 lb. zinc dust;
22 lb. slaked lime, dry.
The vat is set as follows, a part of the lime is mixed with the indigo,
and the two bodies are well mixed together and allowed to stand for ten
minutes, then the zinc powder is added. It is best to make this into a
smooth paste with water before adding it to the other ingredients, then
the rest of the lime is added and the whole is thoroughly stirred
together with the necessary quantity of water.
Vat with zinc powder, lime and soda:--
10 lb. indigo, dry and ground fine;
10 lb. zinc powder;
10 lb. slaked lime, dry;
35 lb. caustic soda at 11° Tw.
Add the lime to the ground indigo, then add the zinc and finally the
soda lye.
Soon after the various ingredients of the vats are added together the
whole mass becomes hot, when it must be well stirred. It soon begins to
evolve gas and the mixture froths. In from two to four hours the
evolution of gas ceases. The dark blue solution now becomes yellow and
the liquor shows all the characteristics of the indigo vat. It is
necessary to keep the vat well stirred up during the time of setting,
which takes from five to six hours. If there is much evolution of gas
after this time it indicates that too much zinc powder has been added;
this is a common fault with dyers, and such excess causes the vat to be
too much disturbed and to work dirty. A lime-zinc vat, with occasional
additions of new materials, keeps good for three months, and even then
is in a better condition than the copperas vat.
This vat is used in precisely the same way as the copperas vat; as it
contains no sediment, or but little, it works cleaner than the copperas
vat and as a rule the indigo blues dyed in it are faster to rubbing.
After a day's work it can be well stirred up and fresh additions of
lime, zinc and indigo made to bring it up to its original dyeing
strength.
=(3) Zinc-Bisulphite Indigo Vat.=--When zinc dust and bisulphite of soda
are mixed together a reaction sets in, the zinc dissolves, and there is
formed sodium hydrosulphite and zinc and sodium sulphites. If now indigo
is mixed with this solution the sodium hydrosulphite exerts a reducing
action on it, forming white indigo and sodium sulphite, a perfectly
clear solution being obtained, which may be used in dyeing cotton or
wool.
With this vat it is customary to prepare a strong stock solution of
reduced indigo, and to add this to the dyeing vats as may be required.
_To Make the Stock Liquor._--Take 20 lb. of indigo, grind into a paste
with 20 gallons of boiled water, then add 25 lb. lime slaked into a
milk. In a separate tub there is mixed 80 lb. bisulphite of soda, 70°
Tw., with 9 lb. zinc dust; this mixture is well stirred and every care
taken to prevent it getting hot. When the zinc has dissolved and the
mixture is free from any sulphurous smell it is run into the indigo
mixture given above. The whole is well stirred together for some time,
and then at intervals, until the indigo has become dissolved, sufficient
water is added to make up 50 gallons, when the stock liquor will be
ready. It should have a deep yellow colour. The surface may have a scum
of a bronzy colour collect on it. This stock liquor should be kept in
casks free from exposure to the air.
To make the working vat from this stock liquor the following is the
method of proceeding:--
Water is run into the vat, and this is heated from 70° to 80° C. in
order to expel air from it, after which it may be allowed to cool, then
for each 1,000 gallons contained in the vat there is added 30 lb.
bisulphite of soda, 3 lb. zinc dust and 3 lb. lime, made into a cream.
When all these ingredients are dissolved a quantity of the stock liquor
is added in proportion to the shade that it is desired to dye. The whole
is well stirred, then the vat is allowed to rest for half an hour to
enable any sediment to settle, and then the dyeing is proceeded with.
Should the vat show signs of becoming green in colour it is a good plan
to add a mixture of 1 lb. zinc dust and 10 lb. bisulphite of soda. The
vat should be kept alkaline, and so a little lime may be added from time
to time.
After a day's work it is well to add a little of the zinc and bisulphite
mixture, to stir well and allow to stand overnight; the next morning
strengthen up the vat by adding fresh stock liquor.
In place of using lime in making up the vat it is possible to use a
mixture of caustic soda and ammonia. The lime will tend to cause some
sediment to form in the vat, whereas the soda and ammonia will not. When
they are used the following mode of working may be followed:--
_Stock Liquor._--Soda zinc vat: Put in a tub 26 gallons cold water, 15
lb. zinc powder ground into a paste with 6 gallons water, then stir in 8
gallons bisulphite of soda at 60° Tw., stir well, keeping the heat down
as much as possible, after which add 8 pints caustic soda lye at 70° Tw.
and 14 pints 20 per cent. liquor ammonia. When all is thoroughly mixed
add 30 lb. indigo, ground into a paste with 7 gallons water, allow to
stand for half an hour, then add water to make 100 gallons, stir at
intervals for twelve hours or so, when the stock liquor will be ready
for use.
This is used to make the vat in the same way as the first above
described. It is needful before adding the stock liquor in making a vat
to destroy any oxygen or air which is present in the vat. This may most
conveniently be done by adding thereto a solution of hydrosulphite of
soda, which may be made by mixing 4-1/2 lb. zinc dust with 5 gallons of
water and 3 gallons bisulphite of soda at 70° Tw., stirring well, so
that the temperature does not rise too high, there is then added 2 pints
caustic soda and 3 pints liquor ammonia, 20 per cent.; when all is
dissolved, water is added to make up 13 gallons.
Should the vat show signs of becoming charged with indigo, indicated by
its becoming of a green colour, a little of this hydrosulphite added
from time to time will correct it.
The hydrosulphite-indigo vat made by either of the two methods indicated
above works well, and with due care may be kept in work for months. It
gives good shades of indigo, although some dyers consider that these
have not the rich bronze hue got from the lime and copperas vat. The
shades are rather faster to rubbing.
It has been proposed to employ the dye-stuff indophenol in conjunction
with indigo, in which case the method of making the vat is with zinc,
bisulphite of soda, caustic soda and ammonia as last described, only in
place of using all indigo a mixture of 22 lb. indigo and 7-1/2 lb.
indophenol is used. Good blue shades of considerable fastness can thus
be got.
_Aniline Black._--This black is produced direct upon the cotton fibre by
various processes which entail the oxidation of aniline. The chemical
composition and constitution of aniline black has not yet been worked
out. It is not by any means an easy colour to dye, but still with
careful attention to carrying out the various operations in detail
excellent results can be attained.
Aniline black is the fastest black which is known, it resists when well
dyed exposure to air and light, is quite fast to washing and soaping.
Its disadvantages are that there is, with some methods of working, a
tendency to tender the cotton fibre, making it tear easily; secondly, on
exposure to air it tends to turn green, this however only happens when
the black has not been dyed properly.
At the present day it is perhaps without doubt the most used of all
blacks. The methods for producing it are many and varied, the following
recipes show how some of the finest aniline blacks can be dyed:--
Ungreenable black is formed when the aniline is by the action of the
oxidising agents converted into a substance named nigraniline. This
compound when formed will not turn green on the fibre under the
influence of acids.
1. The most usual oxidising agent employed for dyeing aniline black is
bichromate of soda, which salt will be found much better for all
purposes than bichromate of potash. Two separate solutions are prepared:
(1) 61 lb. aniline, 9 lb. hydrochloric acid and 10 gallons of water; and
(2) 12 lb. bichromate of soda and 20 gallons of water. After cooling,
equal quantities of these solutions are mixed and the cotton worked
rapidly through the mixture, in a few minutes it assumes a bronze black.
The material is then wrung out and steamed for twenty minutes at 3-1/2
lb. pressure, which process renders it jet black and also ungreenable.
2. Another aniline black: For 100 lb. cotton use 11 lb. aniline oil, 15
lb. bichromate of soda, 40 lb. hydrochloric acid and 160 gallons water
or 12 lb. sulphuric acid. The dye-bath is filled with the water and the
cold solution of aniline oil and a part of the hydrochloric acid in
water is first added, afterwards the bichromate is dissolved in a small
quantity of water, working cold at first and gradually rising to the
boil.
3. Another method is the following and gives a black that is fast and
ungreenable and will not rub: 10 lb. chlorate of soda, 10 lb. ammonium
chloride, 10 lb. copper sulphate, 35 lb. aniline salt, 101 lb. aniline
oil and 20 gallons water. The sodium chlorate and ammonium chloride are
dissolved in 6-1/2 gallons and the copper sulphate separately in 5-1/2
gallons water. The aniline salt is dissolved in as little hot water as
possible and neutralised with a small amount of aniline oil (10 lb.).
The solution of aniline salt is first added to the bath, then the sodium
chlorate and ammonium chloride, and lastly the copper sulphate, dilute
the whole to 14° Tw. and then enter the goods. Next steam, then run
through a solution containing 10 lb. bichromate and 5 lb. soda per 100
gallons water at 160° F., after which the goods are washed and dry
steamed at 15 lb. pressure.
4. A very good black is the prussiate or steam aniline black whose
cheapness should recommend it. Prepare concentrated solutions of 1-3/4
lb. aniline salt in 1 gallon water, 1-1/2 lb. ferrocyanide of potash in
3/4 gallons water and 1-1/2 lb. potassium chlorate in 1-1/2 gallons
water. Mix the solutions and work in a jigger, then steam in a Mather &
Platt apparatus for two minutes, then work hot in a jigger in a solution
of 2 lb. bichromate per 50 gallons water, dry and finish.
Either of these methods yields a good full black; with a little
experience and care perfectly uniform shades will be got.