alum solution. The paper is to be floated for half a minute on this
solution, avoiding air bubbles, and then hung up to dry in a room free
from dust. The purpose of this substratum is to secure additional
brilliancy in the finished prints by keeping the emulsion isolated
from the surface of the paper. The paper should now be cut to the size
desired.
We do not know of these processes having been applied to postal
cards, but unless there is some substance in the sizing of the card
which would interfere, there is no reason why it should not be. Of
course, however, a novice will not get the results by using it that an
experienced hand would.
«Ferro-Prussiate Paper.»—The following aniline process of preparing
sensitive paper is employed by the Prussian and Hessian railway
administrations. The {540} ordinary paper on reels is used for the
purpose, and sensitized as follows:
Two hundred and fifty parts, by weight, of powdered potassium
bichromate are dissolved in water; the solution should be completely
saturated; 10 parts of concentrated sulphuric acid, 10 parts of alcohol
(962), and 30 parts of phosphoric acid, are added successively, and
the whole stirred together. The solution is sponged over the paper. It
is not necessary to have the room absolutely dark, or to work by a red
light, still the light should be obscured. The drying of the paper, in
the same place, takes about 10 minutes, after which the tracing to be
reproduced and the paper are placed in a frame, as usual, and exposed
to daylight. On a sunny day, an exposure of 35 seconds is enough; in
cloudy weather, 60 to 70 seconds; on a very dark day, as much as 5
minutes.
After exposure, the paper is fixed by suspending it for 20 minutes
upon a bar in a closed wooden box, on the bottom of which are laid
some sheets of blotting paper, sprinkled with 40 drops of benzine and
20 of crude aniline oil. The vapors given off will develop the design.
Several impressions may be taken at the same time.
For fixing, crude aniline oil is to be used (anilinum purum), not
refined (purissimum), for the reason that the former alone contains the
substances necessary for the operation. The reproduced design is placed
in water for a few minutes, and hung up to dry.
«Pigment Paper for Immediate Use.»—Pigment paper is usually sensitized
in the bichromate solution on the evening before it is desired for use.
If it is not then used it will spoil. By proceeding as follows the
paper may be used within a quarter of an hour after treating it in the
bichromate bath. Make a solution of
Ammonium bichromate 75 grains
Water 3 1/2 fluidounces
Sodium carbonate 15 grains
Mix 0.35 ounces of this solution with 0.7 ounces alcohol, and with
a broad brush apply to surface of the pigment paper, as evenly as
possible. Dry this paper as quickly as possible in a pasteboard box of
suitable size, 15 minutes being usually long enough for the purpose. It
may then be used at once.
«Photographing on Silk.»—China silk is thoroughly and carefully washed
to free it from dressing, and then immersed in the following solution:
Sodium chloride 4 parts
Arrowroot 4 parts
Acetic acid 15 parts
Distilled water 100 parts
Dissolve the arrowroot in the water by warming gently, then add the
remaining ingredients. Dissolve 4 parts of tannin in 100 parts of
distilled water and mix the solutions. Let the silk remain in the bath
for 3 minutes, then hang it carefully on a cord stretched across the
room to dry. The sensitizing mixture is as follows:
Silver nitrate 90 parts
Distilled water 750 parts
Nitric acid 1 part
Dissolve. On the surface of this solution the silk is to be floated
for 1 minute, then hung up till superficially dry, then pinned out
carefully on a flat board until completely dry. This must, of course,
be done in the dark room. Print, wash, and tone in the usual manner.
«TONING BATHS FOR PAPER.»
The chief complaints made against separate baths are (1) the
possibility of double tones, and (2) that the prints sometimes
turn yellow and remain so. Such obstacles may easily be removed by
exercising a little care. Double tones may be prevented by soaking the
prints in a 10 per cent solution of common salt before the preliminary
washing, and by not touching the films with the fingers; and the second
objection could not be raised provided fresh solution were used, with
no excess of sulphocyanide, if this be the bath adopted.
A very satisfactory solution may be made as follows:
Sodium phosphate 20 grains
Gold chloride 1 1/2 grains
Distilled (or boiled) water 10 ounces
This tones very quickly and evenly, and the print will be, when fixed,
exactly the color it is when removed from the bath. Good chocolate
tints may be obtained, turning to purple gray on prolonged immersion.
Next to this, as regards ease of manipulation, the tungstate bath may
be placed, the following being a good formula:
Sodium tungstate 40 grains
Gold chloride 2 grains
Water 12 ounces
The prints should be toned a little further than required, as they
change color, though only slightly, in the hypo. {541}
Provided that ordinary care be exercised, the sulphocyanide bath cannot
well be improved upon. The formulas given by the various makers for
their respective papers are all satisfactory, and differ very little.
One that always acts well is
Ammonium sulphocyanide 28 grains
Distilled water 16 ounces
Gold chloride 2 1/2 grains
For those who care to try the various baths, and to compare their
results, here is a table showing the quantities of different agents
that may be used with sufficient water to make up 10 ounces:
Gold chloride, 1 gr.
to 1 oz. water 12 dr. 16 dr. 16 dr. 11 dr. 11 dr. 14 dr.
Borax 60 gr.
Sod. bicarbonate 10 gr.
Sod. carbonate 20 gr.
Sod. phosphate 20 gr.
Sod. tungstate 40 gr.
Amm. sulphocyanide 17.5 gr.
We may take it that any of these substances reduce gold trichloride,
AuCl_〈3〉 to AuCl; this AuCl apparently acts as an electrolyte, from
which gold is deposited on the silver of the image, and at the same
time a small quantity of silver combines with the chlorine of the gold
chloride thus:
AuCl + Ag = AgCl + Au
When toning has been completed, the prints are washed and placed in the
fixing bath, when the sodium thiosulphate present dissolves any silver
chloride that has not been affected by light.
Besides the well-known, every-day tones we see, which never outstep the
narrow range between chocolate brown and purple, a practically infinite
variety of color, from chalk red to black, may be obtained by a little
careful study of toning baths instead of regarding them as mere
unalterable machines. Most charming tints are produced with platinum
baths, a good formula being
Strong nitric acid 5 drops
Water 4 ounces
Chloro-platinite of potassium 1 grain
The final tone of a print cannot be judged from its appearance in the
bath, but some idea of it may be got by holding it up to the light
and looking through it. A short immersion gives various reds, while
prolonged toning gives soft grays.
Results very similar to platinotype may be obtained with the following
combined gold and platinum bath:
_A._—Sodium acetate 1 drachm
Water 4 ounces
Gold chloride 1 grain
_B._—Chloro-platinite of potassium 1 grain
Water 4 ounces
Mix _A_ and _B_ and neutralize with nitric acid. (The solution will be
neutral when it just ceases to turn red litmus paper blue.)
Another toning agent is stannous chloride. Two or three grains of tin
foil are dissolved in strong hydrochloric acid with the aid of heat.
The whole is then made up to about 4 ounces with water.
«Toning Baths for Silver Bromide Paper.»—The picture, which has been
exposed at a distance of 1 1/2 feet for about 8 to 10 seconds, is
developed in the customary manner and fixed in an acid fixing bath
composed of
Distilled water 1,000 cubic centimeters
Hyposulphite of soda 100 grams
Sodium sulphite 20 grams
Sulphuric acid 4 to 5 grams
First dissolve the sodium sulphite, then add the sulphuric acid, and
finally the hyposulphite, and dissolve.
Blue tints are obtained by laying the picture in a bath composed as
follows:
_A._—Uranium nitrate 2 grams
Water 200 cubic centimeters
_B._—Red prussiate
of potash 2 grams
Water 200 cubic centimeters
_C._—Ammonia-iron-alum 10 grams
Water 100 cubic centimeters
Pure hydrochloric acid 15 cubic centimeters
Immediately before the toning, mix
Solution _A_ 200 cubic centimeters
Glacial acetic acid 20 cubic centimeters
Solution _B_ 200 cubic centimeters
Solution _C_ 30 to 40 cubic centimeters
Brown tints. Use the following solutions: {542}
_A._—Uranium nitrate 12 grams
Water 1,000 cubic centimeters
_B._—Red prussiate of potash 9 grams
Water 1,000 cubic centimeters
And mix immediately before use
Solution _A_ 100 cubic centimeters
Solution _B_ 100 cubic centimeters
Glacial acetic acid 10 cubic centimeters
Pictures toned in this bath are then laid into the following solution:
Water 1,500 cubic centimeters
Pure hydrochloric acid 5 cubic centimeters
Citric acid 20 grams
«To Turn Blueprints Brown.»—A piece of caustic soda about the size of
a bean is dissolved in 5 ounces of water and the blueprint immersed in
it, on which it will take on an orange-yellow color. When the blue has
entirely left the print it should be washed thoroughly and immersed
in a bath composed of 8 ounces of water in which has been dissolved a
heaping teaspoonful of tannic acid. The prints in this bath will assume
a brown color that may be carried to almost any tone, after which they
must again be thoroughly washed and allowed to dry.
«COMBINED TONING AND FIXING BATHS.»
The combined toning and fixing bath consists essentially of five
parts—(1) water, the solvent; (2) a soluble salt of gold, such as gold
chloride; (3) the fixing agent, sodium thiosulphate; (4) a compound
which will readily combine with “nascent” sulphur—i. e., sulphur as it
is liberated—this is usually a soluble lead salt, such as the acetate
or nitrate, and (5) an auxiliary, such as a sulphocyanide.
The simplest bath was recommended by Dr. John Nicol, and is as follows:
Sodium thiosulphate 3 ounces
Distilled water 16 ounces
When dissolved, add
Gold chloride 4 grains
Distilled water 4 fluidrachms
A bath which contains lead is due to Dr. Vogel, whose name alone is
sufficient to warrant confidence in the formula:
Sodium thiosulphate 7 ounces
Ammonium sulphocyanide 1 ounce
Lead acetate 67 grains
Alum 1 ounce
Gold chloride 12 grains
Distilled water 35 fluidounces
A bath which contains no lead is one which has produced excellent
results and is due to the experimental research of Dr. Liesegang. It is
as follows:
Ammonium sulphocyanide 1/4 ounce
Sodium chloride 1 ounce
Alum 1/2 ounce
Sodium thiosulphate 4 ounces
Distilled water 24 fluidounces
Allow this solution to stand for 24 hours, during which time the
precipitated sulphur sinks to the bottom of the vessel; decant or
filter, and add
Gold chloride 8 grains
Distilled water 1 fluidounce
It is curious that, with the two baths last described, the addition to
them of some old, exhausted solution makes them work all the better.
«ENLARGEMENTS.»
───────────────────────────────────────────────────────────────────────────────
TIMES OF ENLARGEMENT AND REDUCTION
───────+────────+────────+────────+────────+────────+────────+────────+────────
Focus │ │ │ │ │ │ │ │
of │ 1 inch │2 inches│3 inches│4 inches│5 inches│6 inches│7 inches│8 inches
Lens. │ │ │ │ │ │ │ │
In. │ │ │ │ │ │ │ │
───────+────────+────────+────────+────────+────────+────────+────────+────────
2 │ 4 │ 6 │ 8 │ 10 │ 12 │ 14 │ 16 │ 18
│ 4 │ 3 │ 2 2/3 │ 2 1/2 │ 2 2/5 │ 2 1/3 │ 2 2/7 │ 2 1/4
───────+────────+────────+────────+────────+────────+────────+────────+────────
2 1/2 │ 5 │ 7 1/2 │ 10 │ 12 1/2 │ 15 │ 17 1/2 │ 20 │ 22 1/2
│ 5 │ 3 3/4 │ 3 1/3 │ 3 1/8 │ 3 │ 2 9/10│ 2 6/7 │ 2 3/16
───────+────────+────────+────────+────────+────────+────────+────────+────────
3 │ 6 │ 9 │ 12 │ 15 │ 18 │ 21 │ 24 │ 27
│ 6 │ 4 1/2 │ 4 │ 3 3/4 │ 3 3/5 │ 3 1/2 │ 3 3/7 │ 3 3/8
───────+────────+────────+────────+────────+────────+────────+────────+────────
3 1/2 │ 7 │ 10 1/2 │ 14 │ 17 1/2 │ 21 │ 24 1/2 │ 28 │ 31 1/2
│ 7 │ 5 1/4 │ 4 2/3 │ 4 3/4 │ 4 1/5 │ 4 1/12│ 4 │ 3 9/10
───────+────────+────────+────────+────────+────────+────────+────────+────────
4 │ 8 │ 12 │ 16 │ 20 │ 24 │ 28 │ 32 │ 36
│ 8 │ 6 │ 5 1/3 │ 5 │ 4 4/5 │ 4 2/3 │ 4 4/7 │ 4 1/2
───────+────────+────────+────────+────────+────────+────────+────────+────────
4 1/2 │ 9 │ 13 1/2 │ 18 │ 22 1/2 │ 27 │ 31 1/2 │ 36 │ 40 1/2
│ 9 │ 6 3/4 │ 6 │ 5 3/5 │ 5 2/5 │ 5 1/4 │ 5 1/7 │ 5 1/16
───────+────────+────────+────────+────────+────────+────────+────────+────────
5 │ 10 │ 15 │ 20 │ 25 │ 30 │ 35 │ 40 │ 45
│ 10 │ 7 1/2 │ 6 2/3 │ 6 1/4 │ 6 │ 5 5/6 │ 5 5/7 │ 5 5/8
───────+────────+────────+────────+────────+────────+────────+────────+────────
5 1/2 │ 11 │ 16 1/2 │ 22 │ 27 1/2 │ 33 │ 38 1/2 │ 44 │ 49 1/2
│ 11 │ 8 1/4 │ 7 1/3 │ 6 4/5 │ 6 1/2 │ 6 5/12│ 6 2/7 │ 6 3/16
───────+────────+────────+────────+────────+────────+────────+────────+────────
6 │ 12 │ 18 │ 24 │ 30 │ 36 │ 42 │ 48 │ 54
│ 12 │ 9 │ 8 │ 7 1/2 │ 7 1/5 │ 7 │ 6 6/7 │ 6 3/4
───────+────────+────────+────────+────────+────────+────────+────────+────────
7 │ 14 │ 21 │ 28 │ 35 │ 42 │ 49 │ 56 │ 63
│ 14 │ 10 1/2 │ 9 1/3 │ 8 3/4 │ 8 2/5 │ 8 1/6 │ 8 │ 7 7/8
───────+────────+────────+────────+────────+────────+────────+────────+────────
8 │ 16 │ 24 │ 32 │ 40 │ 48 │ 56 │ 64 │ 72
│ 16 │ 12 │ 10 2/3 │ 10 │ 9 3/5 │ 9 1/3 │ 9 1/7 │ 9
───────+────────+────────+────────+────────+────────+────────+────────+────────
9 │ 18 │ 27 │ 36 │ 45 │ 54 │ 63 │ 72 │ 81
│ 18 │ 13 1/2 │ 12 │ 11 1/4 │ 10 4/5 │ 10 1/2 │ 10 2/7 │ 10 1/8
───────+────────+────────+────────+────────+────────+────────+────────+────────
{543}
The object of this table is to enable any manipulator who is about
to enlarge (or reduce) a copy any given number of times to do so
without troublesome calculation. It is assumed that the photographer
knows exactly what the focus of his lens is, and that he is able to
measure accurately from its optical center. The use of the table will
be seen from the following illustration: A photographer has a _carte_
to enlarge to four times its size, and the lens he intends employing
is one of 6 inches equivalent focus. He must therefore look for 4 on
the upper horizontal line and for 6 in the first vertical column, and
carry his eye to where these two join, which will be at 30–7 1/2. The
greater of these is the distance the sensitive plate must be from the
center of the lens; and the lesser, the distance of the picture to be
copied. To reduce a picture any given number of times, the same method
must be followed; but in this case the greater number will represent
the distance between the lens and the picture to be copied, the latter
that between the lens and the sensitive plate. This explanation will be
sufficient for every case of enlargement or reduction.
If the focus of the lens be 12 inches, as this number is not in the
column of focal lengths, look out for 6 in this column and multiply by
2, and so on with any other numbers.
To make a good enlargement five points should be kept constantly in
view, viz.:
1. Most careful treatment of the original negative.
2. Making a diapositive complete in all its parts.
3. Scrupulous consideration of the size of the enlargement.
4. Correct exposure during the process of enlargement.
5. The most minute attention to the details of development, including
the chemical treatment of the enlarged negative.
The original negative should not be too dense, nor, on the contrary,
should it be too thin. If necessary, it should be washed off, or
strengthened, as the case may be. Too strong a negative is usually
weakened with ammonium persulphate, or the fixing hypo solution is
quite sufficient. All spots, points, etc., should be retouched with the
pencil and carmine.
The diapositive should be produced by contact in the copying apparatus.
A border of black paper should be used to prevent the entry of light
from the side.
The correct period of exposure depends upon the thickness of the
negative, the source of the light, its distance, etc. Here there is no
rule, experience alone must teach.
For developing one should use not too strong a developer. The
metol-soda developer is well suited to this work, as it gives
especially soft lights and half tones. Avoid too short a development.
When the finger laid behind the thickest spot, and held toward the
light, can no longer be detected, the negative is dense enough.
The denser negatives should be exposed longer, and the development
should be quick, while with thin, light negatives the reverse is true;
the exposure should be briefer and the development long, using a strong
developer, and if necessary with an addition of potassium bromide.
The silver chloro-bromide diapositive plates, found in the shops, are
totally unsuited for enlargements, as they give overdone, hard pictures.
To produce good artistic results in enlarging, the diapositive should
be kept soft, even somewhat too thin. It should undergo, also, a
thorough retouching. All improvements are easily carried out on the
smaller positive or negative pictures. Later on, after the same have
been enlarged, corrections are much more difficult and troublesome.
«VARNISHES:»
«Cold Varnish.»—
I.—Pyroxylin 10 grains
Amyl alcohol 1 ounce
Amyl acetate 1 ounce
Allow to stand, shaking frequently till dissolved. Label: The negative
should be thoroughly dried before this solution is applied, which may
be done either by flowing it over the solution or with a flat brush.
The negative should be placed in a warm place for at least 12 hours to
thoroughly dry.
II.—Japanese gold size 1 part
Benzol 1 part
Label: In applying this varnish great care should be taken not to use
it near a light or open fire. It can be flowed over or brushed on the
negative.
«Black Varnish.»—
Brunswick black 1 1/2 ounces
Benzol 1 ounce
Label: The varnish should be applied with a brush, care being taken not
to use it near a light or open fire. {544}
«Dead Black Varnish.»—
Borax 30 grains
Shellac 60 grains
Glycerine 30 minims
Water 2 ounces
Boil till dissolved, filter, and add aniline black, 120 grains.
Label: Apply the solution with a brush, and repeat when dry if
necessary.
«Ordinary Negative Varnish.»—
Gum sandarac 1 ounce
Orange shellac 1/2 ounce
Castor oil 90 minims
Methyl alcohol 1 pint
Allow to stand with occasional agitation till dissolved, and then
filter. Label: The negative should be heated before a fire till it can
be comfortably borne on the back of the hand, and then the varnish
flowed over, any excess being drained off, and the negative should then
be again placed near the fire to dry.
«Water Varnish.»—It is not only in connection with its application to a
wet collodion film that water varnish forms a valuable addition to the
stock of chemicals in all-round photography; it is almost invaluable
in the case of gelatin as with wet collodion films. In the case of
gelatin negatives the water varnish is applied in the shape of a wash
directly after the negatives have been washed to free their films from
all traces of hypo, or in other words, at that stage when the usual
drying operation would begin. After the varnish has been applied the
films are dried in the usual manner, and its application will soon
convince anyone that has experienced the difficulty of retouching by
reason of the want of a tooth in the film to make a lead-pencil bite,
as the saying goes, that were this the only benefit accruing from its
application it is well worthy of being employed.
The use of water varnish, however, does away with the necessity of
employing collodion as an additional protection to a negative, and is,
perhaps, the best known remedy against damage from silver staining
that experienced workers are acquainted with. As a varnish it is not
costly, neither is it difficult to make in reasonably small quantities,
while its application is simplicity itself. The following formula is an
excellent sample of water varnish:
Place in a clean, enameled pan 1 pint of water, into which insert 4
ounces of shellac in thin flakes, and place the vessel on a fire or
gas stove until the water is raised to 212° F. When this temperature
is reached a few drops of hot, saturated solution of borax is dropped
into the boiling pan containing the shellac and water, taking care to
stir vigorously with a long strip of glass until the shellac is all
dissolved. Too much borax should not be added, only just sufficient
to cause the shellac to dissolve, and it is better to stop short, if
anything, before all the flakes dissolve out than to add too much
borax. The solution is then filtered carefully and, when cold, the
water varnish is ready for use.
«FADED PHOTOGRAPHS AND THEIR TREATMENT:»
Restoring Faded Photographs.—I.—As a precaution against a disaster
first copy the old print in the same size. Soak the faded photograph
for several hours in clean water and, after separating print from
mount, immerse the former in nitric acid, highly dilute (1 per cent),
for a few minutes. Then the print is kept in a mercury intensifier
(mercuric chloride, 1/2 ounce; common salt, 1/2 ounce; hot water,
16 ounces, used cold), until bleached as much as possible. After half
an hour’s rinsing, a very weak ammonia solution will restore the
photograph, with increased vigor, the upper tones being much improved,
though the shadows will show some tendency to clog. The net result
will be a decided improvement in appearance; but, at this stage, any
similarly restored photographs should be recopied if their importance
warrants it, as mercury intensifier results are not permanent. It may
be suggested that merely rephotographing and printing in platinotype
will probably answer.
II.—Carefully remove the picture from its mount, and put it in a
solution of the following composition:
By weight
Hydrochloric acid 2 parts
Sodium chloride 8 parts
Potassium bichromate 8 parts
Distilled water 250 parts
The fluid bleaches the picture, but photographs that have been toned
with gold do not quite vanish. Rinse with plenty of water, and develop
again with very dilute alkaline developer.
«MOUNTANTS:»
See also Adhesives.
I.—If buckling of the mount is to be cured, the prints must be mounted
in a dry state, and the film of mountant borne by the print must
be just sufficient to attach it firmly to the mount and no more.
The great virtue of the method {545} here described consists of the
marvelously thin film of tenacious mountant applied to the print in
its dry condition, shrinkage by this means being entirely obviated. A
drawing board with a perfectly smooth surface and of fair dimensions,
an ivory or bone burnisher attached to a short handle, with some
common glue, are the principal requisites. Take, say, a quarter of a
pound of the glue broken into small pieces and cover it with water in
a clean gallipot, large enough to allow for the subsequent swelling
of the glue. Place on one side until the glue has become thoroughly
permeated by the water, then pour off the excess and dissolve the glue
in the water it has absorbed, by placing the gallipot in a vessel of
hot water. The solution tested with a piece of blue litmus paper will
show a distinctly acid reaction, which must be carefully neutralized by
adding some solution of carbonate of soda. The amount of water absorbed
by the glue will probably be too little to give it the best working
consistency, and, if this is the case, sufficient should be added to
make it about the thickness of ordinary molasses. Careful filtration
through a cambric handkerchief, and the addition of about 10 grains of
thymol, completes the preparation of the mounting solution. As glue
deteriorates by frequent and prolonged heating, it is preferable to
make up a stock solution, from which sufficient for the work in hand
can be taken in the form of jelly, melted, and used up at once.