with some care, or the prints may become stained. The points calling
for attention are (1) running water and plenty of it, (2) care to
see that the prints do not stick together. What is needed is that
the soluble salts should be washed out of the paper as quickly as
possible, and that the prints be not allowed to remain in the water
containing these soluble salts longer than is necessary. Hence the
advantage of running water and plenty of it. The washing water must
not be too cold or the salts will not pass out of the paper quickly
enough; and again, it must not be too warm or the gelatine will
melt. The best temperature is about 65° F., and the limits should
not go beyond 60° and 70° F., and preferably are kept within 60°
and 65° F. As the paper is usually rather stout, it will need
washing in running or constantly changed water for about ten to
fifteen minutes, and in any case must be continued until all milky
appearance of the water ceases. The print at this stage has a
red-brown colour. If it is now passed direct into the fixing bath
without toning it becomes somewhat more yellow, and when dry is
usually a colour somewhat between yellow ochre and sienna.
_Toning_ is usually our next operation, and for this purpose we have
a variety of toning baths recommended by different workers. The
sulphocyanide and gold is perhaps the chief favourite.
1. Ammonium sulphocyanide 10 to 15 grains.
Gold chloride 1 grain.
Water 8 to 10 ounces.
The proper way to mix this bath is to add the gold to the solution of
sulphocyanide a little at a time. The following method will be found
convenient. As ammonium sulphocyanide is somewhat deliquescent, it is
convenient to keep it in solution. Therefore, one ounce of the salt
dissolved in twenty ounces of (distilled or filtered rain) water
gives us roughly a strength of twenty-two grains per ounce. Dissolve
the contents of a fifteen-grain chloride of gold in fifteen drams of
distilled water. To mix a bath, take of the sulphocyanide solution
half-an ounce; to this add eight ounces of water. Now take one dram
of the gold solution and dilute with one ounce of water. Then add
this dilute gold solution a _little_ at a time to the eight ounces of
sulphocyanide solution, and stir well with a glass rod. It will be
noticed that as the gold solution drops into the sulphocyanide
solution an orange-red precipitate is formed, which is redissolved
on stirring. Hence the gold must be added to the sulphocyanide, and
not _vice versa_.
2. Another favourite bath is as follows:--
Ammonium sulphocyanide 22 grains.
Soda sulphite 2 "
Gold chloride 2 "
Water 20 to 25 ounces.
Instead of weighing out two grains of sulphite it is more convenient
to weigh twenty grains and dissolve in two-and-a-half ounces of
water--_i.e._, at the rate of one grain per dram of solution. Thus,
to mix this bath, take an ounce of the above-mentioned sulphocyanide
solution dilute with twenty ounces water. To this add two drams (1/4
oz.) of the sulphite solution. Then take two drams of the gold
chloride solution and dilute with an ounce of water, and add slowly
with stirring as before.
3. Another favourite bath is:--
Sodium chloride (table salt) 60 grains.
Ammonium sulphocyanide 15 "
Gold chloride 2 "
Water 10 to 12 ounces.
Some of the adherents of this bath recommend that the prints be only
washed in running water for a few minutes and then put into the
toning bath. Others advise the prints to be immersed in the toning
bath without any previous washing--_i.e._, straight from the
printing frame.
4. Here, again, is another bath which usually yields excellent
results:--
Soda phosphate 5 grains.
Sodium chloride (table salt) 20 "
Gold chloride 1 grain.
Water 10 ounces.
5. Other workers omit the sodium chloride and increase the phosphate
and get good tones.
Soda phosphate 20 grains.
Gold chloride 1 grain.
Water 10 ounces.
6. Others, again, combine the phosphate and sulphocyanide baths
thus:--
Sodium phosphate 10 grains.
Ammonium sulphocyanide 15 "
Gold 1 "
Water 10 ounces.
The various toning baths mentioned above have one drawback common to
them all in varying degrees--_viz._, that when once mixed and used
they do not keep in good working order longer than a few hours.
7. The following bath claims to have the advantage that it will keep
in working order for a short time at any rate, but the disadvantage
that it cannot be used until it has been mixed twelve to twenty-four
hours.
Soda acetate 60 grains.
Ammonium sulphocyanide 20 "
Gold chloride 1 grain.
Water 12 ounces.
Toning should be conducted in very weak daylight, or what is much
better, gas or lamplight. The latter, being practically constant,
enables the operator to judge the relative colour of the prints from
time to time. Care must be taken so that the prints do not stick
together in the toning bath, and preferably only a few, say
half-a-dozen or so, dealt with at a time, so that each print can be
frequently turned over and examined. The change of colours proceeds
somewhat slowly at first, but when once it begins it seems to gain
in rapidity of rate of change, so that a careful watch must be kept.
Let it be remembered that the print, after fixing and drying, will
appear a little darker and more blue (less red) than when wet in the
toning bath. The temperature of the bath must not be too cold or
toning is very slow, nor too warm or the gelatine may melt and
toning be uneven. From 60° to 65° F. will be found a convenient
range. The prints should not be touched on their printed surface
more than can be helped. The fingers must be quite clean, the
solutions uncontaminated with other chemicals, and a dish set apart
for toning operations only. This dish should always be washed out
well with tepid or cold water before and after use, and when put
away should rest flat, opening downwards, on a shelf covered with a
sheet of clean blotting paper. Many failures in toning are entirely
due to lack of care in details and sufficient attention to
cleanliness.
When toning is judged to be carried far enough, the prints should be
placed in a roomy dish containing a solution of common salt,
strength one ounce to twenty or thirty ounces of water, to stop
further toning.
Fixing is done with a "one in ten" solution of sodium
thiosulphite--_i.e._, hypo. This should be prepared with tepid
water, or some time before use, as the dissolving of hypo in water
is accompanied by a fall of temperature. A convenient method is to
place a couple of ounces of hypo in a clean pint jug, and add about
half a pint of fairly warm water and stir with a glass rod until the
salt is dissolved, then fill up the jug from the tap with cold
water. It is highly desirable to have plenty of fixing solution, and
never attempt to use the same lot twice. Place each print face down
in the bath and submerge by pressing on its back. Again see that the
prints do not stick to each other, and turn each print two or three
times. They should be in the fixing bath not less than twelve or
fifteen minutes, and a few minutes longer will do no harm. At the
end of, say, fifteen minutes, pour away about one half of the fixing
bath and slowly fill up with water. Turn the prints again, and then
transfer them one by one to another roomy dish and wash in running
water for a couple of hours, or in a dozen changes of water every
five or ten minutes. Then hang up to dry, using either clips or pin
a corner to the edge of a wooden shelf or long lath suspended in a
cool, airy place.
_Alum Bath._--Hot weather considerably increases the danger of the
gelatine melting. To meet this trouble the following plan has to be
resorted to:--
8. Dissolve common (potash) alum, one ounce in a pint of tepid
water. Let it stand until cold and pour off gently the clear part
should any sediment appear. After washing and before toning, place
the prints in this alum bath for about ten minutes and _again_ wash
before toning for ten or fifteen minutes in running water.
_The Combined (Toning and Fixing) Bath._--The general weight of
opinion is _not_ in favour of combining these two operations at one
time when reliable results are desired. Nevertheless, there are
times when this method may be found a convenience and yield results
which are all that may be desired. The following bath is a favourite
with some workers:--
9. Ammonium sulphocyanide 15 grains
Table salt 30 grains
Hypo 2 ounces
Water 10 ounces
To this is _slowly_ added one grain of gold chloride in half an
ounce of water. The prints first washed for five or ten minutes in
running water, and placed in the combined bath and kept moving by
being constantly turned over and over for about ten or fifteen
minutes. The longer they remain in the bath the more blue and less
red will they be when dried.
Here is another bath which finds some stout supporters:--
10. Ammonium sulphocyanide 20 grains
Hypo 1 ounce
Alum 30 grains
Water 10 ounces
Shake well, until thoroughly dissolved, then add
Lead nitrate 20 grains
Again shake well and set aside to settle, pour off the clear part,
and add
Gold chloride 1 grain
dissolved in half an ounce of water.
Others recommend a still more simple bath as follows:--
11. Hypo 1 ounce
Water 8 ounces
Gold chloride 1 grain
It is said that this bath gives better results if it is prepared a
few hours before use, _e.g._, prepared in the morning and used in
the evening. Meanwhile, it should be kept away from daylight, and
not in a very cold place.
_Drying and Glazing._--Some workers are of opinion that it is better
to first "rough dry" the prints, _e.g._, by suspending by clips, or
pinning one corner to a strip of wood, etc., and then to wet again
and dry on a rough or smooth surface according as a matt or glazed
final effect is desired. If however, the print has been through the
alum bath (No. 8.) this preliminary rough drying may not be
necessary.
_Matt Surface._--The matt paper when rough dried has a matt or
slightly rough surface, but it may be desired to accentuate the
effect. This may be done as follows:--Thoroughly clean with soap
water and a nail brush a sheet of "fine-ground" glass similar to
that used for a focussing screen. When quite dry, lightly dust it
with fine talc powder (French chalk) and polish off again with a bit
of clean rag. Now slip this plate rough side up into a dish of cold
water, which also contains the print face downwards. Bring the print
and glass into contact under water, carefully avoiding any air
bubbles between them, as the two together are now raised from the
water; firmly, evenly, but lightly pass a squeegee over the back of
the print now in contact with the glass. Then lightly press a sheet
of blotting paper over the print to take up all adhering water, and
set up in a cool airy place to dry, _e.g._, in a passage or between
the door and half-open window. When quite dry, the print will very
probably of itself come away from the glass, but if not, the finger
nail inserted under one corner and a gently backward pull will
separate it from the glass. In place of the fine ground glass,
rougher glass of course may be employed. Some workers also use for
the same purpose a sheet of roughened celluloid. This is more costly
than glass, but being not so fragile may prove cheaper in the end.
_Glazing Prints_ is done exactly in the same way, with the single
difference, of course, that we use a _smooth_ piece of glass,
vulcanite, celluloid, paper maché slab, sheet of ferrotype metal,
etc., etc., in place of a ground-matt, or rough surface. All the
above-named substances have their partizans; perhaps the greatest
favourite being good plate glass free from scratches. In all cases
it is important to attend to two points, _viz._, thoroughly cleaning
the support and waxing it. Various substances and mixtures have been
recommended for giving a glaze, polish to the glass, etc. Many
workers adhere to the powdered talc or French chalk already
mentioned. Others prefer some of the mixtures given below:--
12. Bees wax 20 grains
Turpentine 1 ounce
13. Spermaceti 20 grains
Benzole 1 ounce
A few drops only of the lubricant are applied to the glass plate
with a bit of clean flannel, and well rubbed all over. Then a final
polish is given with a clean old silk handkerchief, or clean dry
wash leather. On no account attempt to strip the print from the
glass until the print is _quite_ dry or failure is more than likely
to arise.
_Mounting._--Care should be taken that the mountant does not give an
acid reaction. Test with litmus paper. Clearly it is no use being at
the trouble of producing a high gloss on the print if we are going
to damp the print and so destroy the gloss in the operation of
mounting. To avoid this, various plans have been adopted.
(1.) If a cut-out mount is used it will suffice if the print be
attached to the mount by glue at the edges only of the "cut-out."
(2.) Another method is to paste down on to the back of the print
before it is quite dry, and while still on the glazing support, a
backing of thin waterproof paper specially prepared for this
purpose. This prevents the moisture of the mountant penetrating to
the print. (3.) Another plan is to use a mountant which does not
contain water. The following mixtures are recommended:--
14. Masticated rubber 10 grains
Benzole 1 ounce
A thin layer of this is applied by means of a short, stiff, flat
hog's hair brush to the back of the print. It is then allowed to
evaporate for a minute or so, and when tacky is applied to the
mount, covered with a sheet of glazed paper, and a roller squeegee
passed over the surface.
15. Saturated solution of bleached shellac in alcohol.
This must be applied as thinly as possible.
16. Le Page's fish glue applied to the edges only of the
back of the print.
A fourth method is to first carefully clean the edges of the glass
surrounding the print still adhering to it. Then to paste down the
mount to the print and let all dry. Then strip the print from the
glass now already mounted. This is, however, a process not to be
recommended, because requiring a long time for the print to dry, as
the evaporation has to take place through the substance of the
mount.
ADDITIONAL PROCEDURES WITH P.O.P.
_Development of Partially Printed Proofs._--This method of procedure
is sometimes a matter of convenience in dull weather, etc. The
printing is to be carried on until one can just see a very slight
indication of detail in the high-lights. It is then washed in
running water for about ten minutes, and then put into a ten per
cent. bath of potassium bromide, and there it remains for another
ten minutes or so. In this bath some of the image seems to fade
away, and generally the print takes on a yellow tinge. The print is
next washed in running water for about ten minutes, and then
developed with ortol, metol, or preferably, hydroquinone. A
considerable variation in the proportions of the constituents of the
developer are possible. In general terms, one may say that a
developer which gives a good black and white lantern slide when
diluted with about an equal quantity of water will give a
satisfactory print.
17. As an example of a thoroughly practical developer for this
purpose we may give just one example:--
A
Hydroquinone 70 grains
Potassium metabisulphite 5 "
Potassium bromide 30 "
Water 20 ounces
B
Soda sulphite 1 ounce
Caustic soda 60 grains
Water 20 ounces
Take equal parts and mix just before use, wash for at least ten
minutes in running water at once after development.
Developed prints may be toned in the combined bath 9, 10 or 11, or
may first be fixed, then _thoroughly_ washed, and then toned and
again washed.
If good results are wanted by the development process it is
important to be careful that the paper is not exposed even to weak
daylight more than can be helped, and not even to strong artificial
light more than is necessary. At the same time it is quite
practicable to do the operation of the bromide bath and developing
in fairly strong gaslight, _i.e._, one need by no means be limited
to the ordinary dark-room light as when developing plates.
Another point worth noting is that it is quite practicable to use
magnesium ribbon for printing. For a rather thin negative it will be
perhaps found sufficient to burn about a foot of the metal ribbon
about three or four inches from the glass. The printing frame should
be set up on edge in the vertical plane. The strip of metal ribbon
is held by a pair of pliers, and ignited at the flame of a candle or
spirit lamp. The lid of a biscuit box just in front of the frame
does very well to catch the white magnesium oxide formed by burning.
It is as well to move the flame of the burning metal opposite
various parts of the negative during the exposure. It will be found
a comfort to wear a pair of rather dark blue glasses during this
operation, as the bright light of combustion prevents one seeing
anything with ease for a little while.
After development the print may be fixed only, and under certain
conditions it is possible to obtain a fairly satisfactory black or
brown colour without toning, but there is usually a slight tendency
towards rather too much yellow.
_Platinum Toning._--This method of toning is a favourite with many
workers. By it a considerable variety of colour tones may be
obtained, from a rich red chocolate brown through sepia brown to a
warm black.
The following toning baths have each their several advocates, and
each worker must discover by experiment the one that gives him the
particular brown colour he prefers:--
18. Potassium chloroplatinite 1 grain.
Water 1/2 ounce.
Add dilute nitric acid (one part strong acid, twenty parts water)
drop by drop until the mixture just turns a bit of blue litmus paper
a red tinge. Now take a glass rod and make of it a mop by tying a
small bunch of clean cotton wool over one end, using for the purpose
a bit of white cotton. Having thoroughly washed the print for _at
least_ ten minutes in running water, lay it face up on a sheet of
glass, and apply the above toning solution with the cotton wool mop.
Having got a tint or colour nearly what you want, but allowing for a
loss of red in fixing, wash off the toning solution and immerse the
print in:--
19. Washing soda 1 ounce.
Water 10 "
for three or four minutes, and then fix in the usual way in a ten
per cent. hypo bath.
Here are some platinum toning baths well recommended:--
20. Lactic acid 2 drams.
Water 12 ounces.
Pot. chloroplatinite 2 grains.
21. Citric acid 20 grains.
Water 10 ounces.
Table salt 20 grains.
Pot. chloroplatinite 2 grains.
22. Phosphoric acid 3 drams.
Water 10 ounces.
Pot. chloroplatinite 2 grains.
The chief points to bear in mind in platinum toning are: (1) that
the print must have practically all the free silver washed away
before toning. To this end it is a very good plan to dip each print
for a couple of minutes or so in a bath of table salt one ounce,
water ten ounces, and again rinse under the tap for a minute or
two.
(2) That the toning bath is acid, therefore one must either
neutralize this acidity by passing through an alkaline bath, such as
No. 19, or what perhaps is rather more convenient, though not quite
so desirable--_i.e._, using a fixing bath made distinctly alkaline.
The following proportions are recommended:--
23. Hypo 1 ounce.
Water 10 ounces.
Soda sulphite 1/2 ounce.
Washing soda 1/2 "
_Toning with Gold and Platinum._--A large number of experimenters
have tried to find out how to produce platinotype-like effects with
P.O.P. papers. Perhaps none of them have been completely successful.
The following procedure, however, seems to give the nearest approach
to that ideal.
The best results are obtained with a slightly matt-surfaced paper.
This should be printed a shade or two deeper than the print is
intended to appear finally. The print is well washed and then
_partly_ toned in a gold bath:--
24. Soda acetate 30 grains.
Borax 25 "
Water 10 ounces.
Gold chloride 1 grain.
It is then washed for a minute or so, and the toning continued in
the following bath.
25. Phosphoric acid 1 dram.
Water 5 ounces.
Pot. chloroplatinite 2 grains.
Wash for five minutes and fix in bath 23.
_Intensifying and Reducing P.O.P._--When the negative is obtainable
and printable it is _very_ much better, and altogether more
satisfactory to make a fresh print than to attempt to intensify or
reduce an unsatisfactory one.
Nevertheless, it sometimes happens that this course is not possible,
and the best has to be made from an unsatisfactory print.
If the print is only very lightly printed, and comes straight from
the printing frame, it is best to strengthen it by development (see
formula 17 _et seq._). If the print has been toned and fixed, etc.,
the following may be tried:--
26. Make a _saturated solution_ of mercury bichloride in cold water,
let it settle, and use only the quite clear supernatent liquid.
Immerse the print in this for 15 minutes, turning it from time to
time, and see that no air bells are clinging to either side. Wash
the print in running water for 15 minutes at least, and longer if
convenient. Then immerse it in a bath consisting of strong ammonia
one part, water ten or twelve parts. Again wash for five minutes
under the tap.
_Reducing P.O.P._--
27. Hypo 120 grains (120)
Uranium nitrate 4 "
Water 2 ounces.
The advocates of this solution claim for it that it can be used
either _before_ or _after_ toning with equal facility and advantage.
Prints must be well washed both before and after its use in any
case.
Another method, which is somewhat risky except in expert hands, is
as follows:--
28. Dissolve metal iodine in alcohol to a rich dark port wine
colour. Dilute a small quantity with cold water until the whole is a
pale sherry colour. Now prepare a one in ten solution of potassium
cyanide (_N.B.: a powerful poison_) and add this a _little_ at a
time until the pale yellow colour of the iodine solution is just
discharged.
The print may be immersed in this until sufficiently reduced, or it
may be applied locally with cotton wool mop (as described above
under platinum toning formula 18). The print must of course be
quickly washed just before the desired degree of reduction has been
produced. This solution acts somewhat quickly when once the action
begins, and therefore it is well to deal with prints one at a time.
DEFECTS, ETC.
_Red-orange_ patches are usually due to touching the gelatine
surface with dirty fingers, etc. These places, being somewhat
greasy, repel the various fluids and cause uneven action of the
developing, toning, etc.
_Brown Stains_ are also often produced in the same way. They may
_sometimes_ be removed by the application of a saturated solution of
alum. If this fails one may try "chloride of lime" ("bleaching
powder") one part in twenty parts of hot water. Allow to stand until
cold and apply with cotton wool mop.
_Yellow Stains_ may sometimes be removed by a dilute solution of
potassium cyanide (poison) of strength one part cyanide in fifty
parts water. (Yellow stains usually indicate hypo splashes.)
_General Fog from Age._--This sometimes may be considerably reduced
by giving the prints the bath of: Soda sulphite (one in fifteen)
_before_ toning, but well washing after this bath and before toning.
_Very Slow Toning_ generally points to the fact that the toning bath
is too cold, or that it has been spoilt by a small quantity of hypo
or developer, or that it does not contain sufficient gold.
_Uneven Toning, i.e._, blue edges, generally points to a bath too
strong in gold, or that there are too many prints in the bath at
once, so that the edges are getting more of the metal than the
central parts, or it may arise from prints sticking together or to
the bottom of the dish.
_Blue-Grey Tones_ indicate too long a time in the toning bath, or a
bath too strong in gold.
_Red-Yellow Tones_ arise from just the opposite state of affairs.
_Pinking_ of the high-lights points to the bath being too weak or
becoming worked out.
_Double Toning_, _i.e._, the print shewing different colours, points
to insufficient washing or uneven action of the toning bath, _i.e._,
not keeping the prints moving, or too slow toning, or that the
toning bath does not suit the brand of paper.
_Blisters_ are usually due either to using a hypo fixing bath too
strong, or passing the print from one solution to another of a
markedly different temperature. Hence the importance of dissolving
the hypo either in tepid water or some time before use. The best
all-round temperature for working this process is between the limits
of 60° and 65° F.
_Tinting P.O.P._--The colours to be used may be the usual moist
water colours by some good maker, or solutions of aniline colours.
These latter may usually be dissolved in water and applied in thin
washes. The surface of the print should be rubbed as little as
possible. If water colours are to be used it will be found helpful
to prepare the surface of the print with one or other of the
following preparations.
29. White (bleached) lac. 1 part
Alcohol 12--15 parts
Apply evenly and quickly with a spray diffuser or with a broad soft
brush, and let the print become _nearly_ dry before applying the
colours.
30. The white of an egg in twenty ounces of water. Shake well, then
add ammonia drop by drop until the mixture just very faintly smells
of it. Filter and brush over the surface of the print. In mixing the
water colours also use this albumen solution in place of water.