PhotoHistory

From: THE BARNET BOOK OF PHOTOGRAPHY

By Rev. F. C. Lambert, M.A. 1898

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 percent, 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.

As an example of a thoroughly practical developer for this purpose we may give just one example:

Part A
Hydroquinone 70 grains
Potassium meta-bisulphite 5 grains
Potassium bromide 30 grains
Water 20 ounces

Part 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 with toner, 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 gas-light, 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 color without toning, but there is usually a slight tendency towards rather too much yellow.

Platinum Toning

This method of toning is a favorite with many workers. By it a considerable variety of color 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 color he prefers:

Platinum Toner #1
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 color nearly what you want, but allowing for a loss of red in fixing, wash off the toning solution and immerse the print in:

Washing soda 1 ounce
Water 10 ounces

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:

Platinum Toner #2
Lactic acid 2 drams
Water 12 ounces
Potassium chloroplatinite 2 grains

Platinum Toner #3
Citric acid 20 grains
Water 10 ounces
Table salt 20 grains
Potassium chloroplatinite 2 grains

Platinum Toner #4
Phosphoric acid 3 drams
Water 10 ounces
Potassium 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, 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:

Hypo 1 ounce
Water 10 ounces
Soda sulphite 1/2 ounce
Washing soda 1/2 ounce

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 mat 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:

Soda acetate 30 grains
Borax 25 grains
Water 10 ounces
Gold chloride 1 grain
It is then washed for a minute or so, and the toning continued in the following bath:

Phosphoric acid 1 dram
Water 5 ounces
Potassium chloroplatinite 2 grains
Wash for five minutes and fix.

Intensifying 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. If the print has been toned and fixed, etc., the following may be tried:

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.

Hypo 120 grains
Uranium nitrate 4 grains
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:

Dissolve metal iodine in alcohol to a rich dark port wine color. Dilute a small quantity with cold water until the whole is a pale sherry color. 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 color 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). 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 power”) 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 showing different colors, 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 degrees F.

Tinting P.O.P.

The colors to be used may be the usual moist water colors by some good maker, or solutions of aniline colors. 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 colors are to be used it will be found helpful to prepare the surface of the print with one or other of the following preparations.

#1
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 colors.

#2
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 colors also use this albumen solution in place of water.
Advantages of P.O.P.

As compared with ordinary albumenized silver paper the P.O.P. class has the advantage of giving more detail with marked transparency in the shadows. The operations are more flexible and the results are as permanent, if not more so, than those on albumen paper. The paper keeps in good condition for a longer time. The negative giving the best results with P.O.P. is one having delicacy rather than vigour, i.e., a long scale of gradation of delicate steps is well rendered. Printing takes place quicker with P.O.P. than with albumen papers. The cost of paper and materials is much about the same in both instances.

Notes

In the glazed variety of paper the smooth shiny surface is the sensitive one, and, of course, goes next the negative in the printing frame. In the mat paper the sensitive side may generally be known by its tendency of curling inward, i.e., the concave or hollow side is the printing side.

Formalin may be used in place of alum for hardening the gelatine. Of the usual 40 percent solution of formalin take one ounce and dilute with ten or twelve ounces of water.

Dark spots or specks are frequently due to metallic dust either from the fingers or in the water. Mounts having sham gold edges or bronze powders should be banished from the dark-room. Dry “pyro” floating in the air may also account for spots.