Notwithstanding the unprecedented progress of the coal-tar dyestuff
industry during the past few decades, the time-honored indigo, logwood,
fustic, etc., have been only partly displaced by the coal-tar products in
wool dyeing. The cause is that, though the dyer handled many aniline
dyestuffs which dyed as fast against light as logwood or fustic, the dye
proved unsatisfactory for fulling goods, because it bled in the treatment
with soap and soda, and often more or less changed its tone. We intend to
render a service to our readers by calling their special attention to
some products of the coal-tar industry which are free from these defects
of aniline dyestuffs, and for which it is claimed that they far surpass
logwood, fustic, cudbear, etc., as to fastness against light, and
excellently stand fulling. We allude to the alizarine dyestuffs, which
have long since been introduced and are largely employed in cotton dyeing
and printing.
Alizarine, which has been extensively discussed in various articles in
our journal, is the coloring matter contained in the madder root. In
1869, two German chemists, Graebe and Liebermann, succeeded in
artificially producing this dyestuff from anthracene, a component of
coal-tar. The artificial dyestuff being perfectly pure and free from
those contaminations which render the use of madder difficult, it soon
was preferred to the latter, which it has at present nearly completely
displaced.
The discovery of alizarine red was soon followed by those of alizarine
orange, galleine, coeruleine, and, in 1878, of alizarine blue.
The slow adoption of these dyestuffs in the wool-dyeing industry is
principally attributable to the deep-rooted distrust of wool dyers
against any innovation. This resistance, however, is speedily
disappearing, as every manufacturer and dyer trying the new dyestuffs
invariably finds that they are in no respect inferior to his fastest dyes
produced with indigo and madder, but are simpler to apply and more
advantageous for wool.
The alizarine colors are dyed after an old method which is known to every
wool dyer. The wool is first boiled for 1½ hours with chromate of potash
and tartar, then dyed upon a fresh bath by 2½ to 3 hours' boiling. All
alizarine colors (such as those of the Badische Anilin und Soda Fabrik,
of Ludwigshafen and Stuttgart; Wm. Pickhardt & Kuttroff, New York,
Boston, and Philadelphia, viz.):
Alizarine orange W, for brown orange,
Alizarine red WR, for yellow touch ponceau or scarlet,
Alizarine red WB, for blue touch yellow or scarlet,
Alizarine blue WX and SW, for bright blue,
Alizarine blue WR SRW, for dark reddish blue,
Coeruleine W and SW, for green, and
Galleine W, for dahlia,
are dyed after the same method, which offers the great advantage that all
these colors can be dyed upon one bath, and that by their mixture
numerous fast colors can be produced. On the ground of numerous careful
experiments, the writer recommends the following method, which gives well
developed and well fixed colors, viz.:
For 100 kil.--The scoured and washed wool is mordanted by boiling for 1½
hours in a bath containing 3 kil. chromate of potash and 2½ kil. tartar,
and lightly rinsed; when it can immediately be dyed. For 1,000 lit.
water, 1 lit. acetic acid of about 7° Be. is added to the bath. If the
water is very hard, double the quantity of acetic acid, which is
indispensable, is added. Then the required quantity of dyestuff is added,
well stirred, the wool entered, and the temperature raised to boiling,
which is continued for 2½ to 3 hours, that is, until a sample taken does
no longer surrender any color to a hot solution of soap. Loose wool and
worsted slubbing can be entered at 60° C. (140° F.). In dyeing yarn and
piece-goods, however, it is advisable to enter the bath cold, work for
about 1/4 hour in the cold, and then slowly to raise the temperature in
about one hour to the boiling point. With this precaution, level and
thoroughly dyed goods are always obtained. If the wool is entered in a
hot bath, or if it is rapidly brought to a boil, the dyestuff is too
rapidly fixed by the mordant and is liable to run up unevenly, and, with
piece-goods, more superficially. For the same reason the goods must
always be well wetted out before entering the bath.
We add some special recipes for the various colors, the mordant for all
of them being of 3 per cent. chromate of potash and 2½ per cent. tartar
for 100 by weight of dry wool.
1. _Orange, Brown Touch_.
20 kil. wool, mordant with 600 grm. chromate of potash and 500 grm.
tartar, dye with 3 kil. alizarine orange W.