Part 13

_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.

_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 matt paper the sensitive side may generally be known by its tendency to curl 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 per cent. 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.

_Rev. F. C. Lambert, M.A._

_Platinotype Printing._

Amongst the various printing processes in common use amongst photographers, platinotype is unique in several respects.

Printing is conducted by daylight in precisely the same manner as silver printing, but the action of light only suffices to make the image partially visible. In this respect, platinotype stands, as it were, midway between what are familiarly termed "print-out" processes--that is, those in which the image is made completely visible by daylight, and those in which the action of light is latent or invisible, such as bromide paper and in the carbon process.

The distinctive character of the platinotype print, with which, probably, everyone is so familiar that a platinotype effect almost amounts to a generic term, is not so much essential to the process, but has been largely determined by the different kind of papers and the preparation of those adopted by the manufacturers of platinotype printing papers.

In the first place, the platinotype print is before anything a matt surface print, and possesses a certain kind of texture or surface which gives the finished print an appearance similar to a pencil drawing or an engraving; an appearance largely assisted by the characteristic colour of the platinum image, which is black.

The invention and production of platinotype paper is due to Mr. Willis and the Platinotype Company, and although subsequently there have been both English and foreign imitators, we may safely confine our attention to those papers made and supplied by the Platinotype Company.

As, however, the purpose of this article is to furnish the beginner with simple working instructions, rather than to describe the principles of the process, we will at once proceed to say how a platinotype print is made.

To begin with, platinotype printing is divided into cold-bath process and hot-bath process. Of the latter we shall speak later on, but for the present, as being most suitable for the amateur and beginner, we will consider the cold-bath method. The reason for this division and the meaning of the name will be abundantly evident presently.

We first of all procure a tin of paper of the quality marked AA. The paper is put up in tin cylinders containing twenty-four pieces of either 1/4-plate or 1/2-plate sizes, or less for larger sizes. It may, if preferred, be obtained in full-size sheets 20 × 26 inches.

We have now to bear in mind that the paper is sensitive to daylight to a slightly greater degree than are the silver print-out papers, and hence, whilst handling the paper, placing it in the printing frames, or what not, we need to be a little more careful as to how near the window we bring the paper. At the side of the room furthest from the window, or with an intervening screen between the paper and the window, or yet again, with the blind drawn down, we shall be quite safe in opening our tin of paper and inspecting it.

On removing the lid of the tin we find a false top or cover hermetically sealing it, which has to be cut through in the manner becoming customary with various tinned foods and comestibles.

We then find that the paper within is yellow on one side which is the sensitive side. Within the roll of papers at the bottom of the tin we shall find a hard irregular lump of some substance wrapped round with cotton wool. Keep this in the tin and now note its use from the following:--Platinotype paper is highly susceptible to moisture and deteriorates under its influence. The air we breathe, and therefore the air enclosed within the tin case or any other vessel contains a large amount of moisture, and this moisture would be taken up by the platinotype paper to its own detriment. The presence of water or moisture in the atmosphere or in things we handle, although quite unperceived by us, would be discoverable by the platinum salts on the paper, which would thus become unfit for use, hence the only way of preserving it is by placing in the tin containing the paper some chemical which is even more susceptible to moisture than platinotype paper. Such a body is calcium chloride, and this it is which we find wrapped in cotton wool in each tin tube of paper, or to speak more accurately it is asbestos prepared in a solution of calcium chloride. So long as that little lump remains dry and hard we may be quite sure that it has left no moisture in the air around it for the platinotype paper, and it will go on drinking it up until it becomes softened by saturation, when it must be removed and a fresh piece substituted, or it may be restored to its former condition by drying it on a red-hot shovel, the asbestos remaining unconsumed.

Whilst perhaps in after practice we may find it possible to relax our precautions against damp, yet at the outset the necessity of the utmost caution being observed cannot be too strongly insisted upon. Out of a very large number of prints representing the beginner's first attempts at platinotype, by far the greatest number of failures are due to damp, and this, probably, for want of conception of the danger to which the paper is exposed. Remember then that where there is ordinary air there is also abundant moisture, and as no tin box with a movable lid is air-tight, neither is it moisture-proof, but in the case of our tin of platinotype paper when once opened will go on admitting moisture which the calcium chloride will take up until it can take no more.

After having cut through the inner sealed top of the tin, close up the little hole in the outer lid where the cutting point is with sealing wax, next cover the mouth of the tube with a piece of waxed paper or tinfoil, shut the lid down on to this, and then cover the junction of the lid with a broad indiarubber band. In this way damp may be prevented from gaining access to the inside of the tube to a great extent.

Specially constructed tubes are made which close with an air-tight stopper and have a false bottom with a perforated partition in which the calcium chloride may be kept. Such a "calcium-tube," as it is called, if not an absolute necessity, is a very desirable acquisition.