Part 15

Next we have the papers for Hot-Bath process, to be presently described. These are firstly A and C, both precisely the same in character as the AA and CC just referred to, but intended to be developed in a bath at high temperature. These four kinds of paper all yield a picture of the normal platinotype black colour, the black tending to cooler or warmer tints according to slight modifications of treatment, but it is also possible to produce a platinotype print of a rich sepia brown by using the papers S and RS--these both in substance and character corresponding with AA or A and CC or C respectively. Thus we have a thin smooth and a thick rough paper for each Cold bath, Hot bath, and for Sepia printing.

DEVELOPMENT OF HOT-BATH AND SEPIA PAPERS.

With the Hot-Bath papers perhaps the precautions against damp should be rather more stringent than for Cold-Bath papers, certainly they may not be relaxed, and in the sepia papers, S and RS, there seems to be even greater susceptibility still, but for this, printing and development are performed precisely as already described, but the temperature of the oxalate bath should not be less than 150° to 170°, whilst in some cases it may be convenient to raise it still higher. The oxalate solution should, moreover, always be at full strength, namely, 1/2 lb. in 25 ozs. of water or thereabouts, a much more diluted bath will result in granular prints.

As a general rule the colour of A and C prints is a rather browner black than their cold-bath equivalents--AA and CC--with also rather softer contrasts.

Development takes place in shorter time than with cold-bath papers, and is indeed so instantaneous that any control is next to impossible. On this account, rather more dexterity will be required in development, that is to say, between the time that one end of the print touches the developer and the rest of the print is brought into contact with it, the shortest possible time should elapse. There must be no hesitation, the whole surface must be brought down gradually but swiftly, and accompanied by a sliding movement in order to squeeze out or wipe out any air bubbles which might cling to the surface of the paper. If this be not done evenly and continuously, it is more than likely that there will be marks of unequal development on the surface.

It is no uncommon thing for the tyro to let the print hover over the bath before giving it its plunge in the hot solution, but in so doing it should be remembered that he is submitting it to the direct action of the steam which the bath is giving off, and so exposing it to damp.

Whilst with prints of 1/2-plate size and under it may be sufficient to hold the print by one corner and wipe it across the surface of the solution, pressing it down with the fingers of the other hand, with larger sizes it will be well to cultivate a little trick in manipulation, and the accompanying figure may perhaps be suggestive (Fig. 5), in which it will be seen the left hand is bringing one end of the print into contact with the bath, whilst the right hand holds the opposite end above and well back, and the left hand will next be moved in the direction of the arrow, drawing the print with it along the surface of the bath, the right hand following but simultaneously lowering the whole of the print--thus the solution attacks the print smoothly and continuously, whilst the air is pressed out in the opposite direction. Instantly the entire print is floating on the bath it should be moved about a little, as a further means of disengaging any air bubbles.

As far as possible, prevent the developer from flowing over the back of the print, but this will be a far less evil than not bringing the whole printed surface immediately and at one stroke on to the developer. The print is next passed direct and without intermediate washing into the hydrochloric acid bath, as already described.

The sepia papers, S and RS, are both hot-bath papers, and no special instructions need to be given as regards development, except that to get the full benefit of the sepia tint and secure a fine rich bright colour, the Special Sepia Solution prepared and supplied by the Platinotype Company should be employed in the developer.

Of this, one or two drams should be added to each ounce of oxalate bath, either before heating it in the dish or afterwards and just before floating the prints. In the latter case stir the whole so as to get it equally mixed, and wipe the surface to remove any scum.

A good substitute for the bath as above prepared for sepia prints may be made by adding one part of saturated solution of oxalic acid to each ten parts of oxalate of potash solution.

The Sepia papers are rather more sensitive to light than the Black papers, and hence all operations should be conducted in very subdued daylight, a precaution even extending to the first acid bath.

The bath containing the special solution should be used for sepia prints only, and when done with kept in a separate bottle for future use, but the bottle must be kept from the light, and the sediment which will fall should be left undisturbed at the bottom of the bottle or filtered out, and the dish used for sepia development should be well washed before using it for black prints.

Opinions seem to differ as to the wisdom of keeping old developing baths, but as far as my own experience goes I use the oxalate solution for black prints again and again, taking no heed of its discoloured condition.

After developing, the bath is poured into the stock bottle, and so long as undissolved crystals remain at the bottom of the bottle hot water may be added from time to time to make up the loss occasioned by spilling and waste, thus the stock solution is always a combination of old and freshly-dissolved oxalate, and I have had one large jar of solution thus in very frequent use for over twelve months, a greenish-black encrustation gradually accumulating at the bottom without detriment.

CONCERNING THE HYDROCHLORIC CLEARING OR FIXING BATH.

Little needs to be said as to the Hydrochloric Acid bath into which the prints are passed immediately after development. The purpose of the acid bath is to dissolve out the sensitive salts which have been unaffected by light and which are still light-sensitive, the removal of these making the paper white and clean. Thus the acid bath is both fixing and clearing in its action.

Into the first acid bath the prints will carry a good deal of the oxalate solution in which they have been developed, and it therefore soon becomes very much discoloured, wherefore after a lapse of about five minutes the print should be removed to a second acid bath of the same strength as the first (pure hydrochloric acid 1 part, water 70 parts) and after five or ten minutes into a third.

After the prints (many may be done at the same time) have been in the third acid for five minutes, the bath should be examined, and if it is quite colourless, that is if the prints have not discoloured it at all, we may rest satisfied that clearing and fixation are complete, but if not, yet another acid bath should be given.

Whilst five or ten minutes in each acid bath is long enough, probably no harm to the print itself, yet no good, will follow a longer immersion. There may, however, be a danger of softening or rotting the paper, a danger which is increased should the bath be made stronger in acid.

If a number of prints are being made, or if numerous dishes for acid constitute a difficulty or inconvenience, we may modify procedure as follows:--

Make up the first acid bath to about half the prescribed strength, say hydrochloric acid one part to water 120 to 140 parts. Into this each print may be flung as soon as developed, until the entire batch is thus far finished. In this weak acid bath the prints will take no harm if left for several hours, when an acid bath (one to seventy) of full strength having been prepared, the first weak solution may be poured off and the fresh poured on. In this the prints should be separately turned over, so that each receives thorough treatment, when the second bath may be thrown away and a third substituted. One dish thus serves for the whole series of acid baths.

If adopting this course, it will be safer not to mix sepia and ordinary black prints in the same _first_ acid bath, after which, however, they may be treated altogether.

Sufficient washing to rid the paper of acid is all that is required to complete operations; but acid does not cling to the print as does hypo, moreover, we have not an absorbent gelatine surface to deal with, so that if prints were dealt with individually and washed by hand, probably a few minutes sluicing under a tap would suffice, but in a properly constructed print-washer, or even a large dish, twenty minutes to half-an-hour should be ample. If any doubt is felt, the last washing water may be tested with blue litmus paper.

MODIFICATIONS IN DEVELOPMENT.

To impart a warmer and richer tone to prints on CC (cold-bath) paper, the following slight modification may be resorted to, but it must be regarded merely as an exception for definite purposes, being in violation of the instructions and rules already laid down. It consists of developing CC paper as though it were hot-bath paper, using a bath of about 170° F and submitting it to the influence of damp to a slight degree. This latter very heterodox course may be effected by leaving the paper laid out all night in a room where there has been no fire to dry the air, or by using paper which has been kept for a week or so in its tube without calcium chloride and without sealing the lid, or yet again, the print may be held over the steam of the developer for a few minutes before developing it.

It must be remembered that in doing this we are taking liberties with the process, and if poor, "muddy" prints result, we can only blame ourselves, but as a rule this will not be the case, the effect being rather to impart a slight creamy tone to the whites without otherwise degrading their brilliance, whilst the use of a hot bath gives the whole a distinctly brown-black image, which combined with the cream tint of the high-lights has a very luminous and warm effect.

Another method of development which must also be taken as an exceptional one, only to be used in special cases to attain special ends, is local development with a brush, using glycerine as a medium.

As may have been seen from the foregoing descriptions, the development of a platinotype print, even with a cold bath, is so rapid that there is not a possibility of developing one portion more than another, or if such could be done, still it would be done with the certainty of leaving a mark where development had been stopped. These difficulties, however, may be overcome by the use of glycerine, the effect of which is to retard development to almost any degree, and by its soft, viscid character to soften and blend the line of demarcation where greater or less development ceased. The method of applying it is as follows: On removing the print from the frame it should be fastened to a board with pins, print side upwards. Next pour on to the surface a small pool of _pure_ glycerine, and with the finger tip, a brush or soft pad, spread it _evenly_ and thinly over the print. It must not be allowed to remain on the surface in irregular patches of unequal depth, but after spreading it had better be wiped with a fresh pad of cotton wool, so as to remove any superfluous glycerine. Now have four small vessels at hand, and into No. 1 place an ounce or two of the ordinary oxalate developing solution, in No. 2 put equal parts of oxalate solution and glycerine, in No. 3 one part oxalate solution and two parts glycerine, and in No. 4 pure glycerine.

With a broad, soft hair brush apply the contents of No. 3 to the less printed portions of the image and wait results. These portions will presently begin to gain in depth and to slowly develop up, now spread the No. 3 mixture to the rest of the print and apply the contents of No. 2 to the portions first treated with No. 3. The most obstinate parts may be touched with No. 1, plain oxalate solution, whilst any spots which have come up too quickly may be promptly arrested from further progress by the application of pure glycerine.

Here we have a method of developing up any one part, and restraining or entirely stopping any other.

I do not think any good will be done by a more detailed description of its working, even if there be anything more to tell. It is essentially a method of development in which the individual worker will invent modifications and dodges for himself, and when all is said for it, it must be admitted only as a means of improving a subject when ordinary procedure fails.

THE CHARACTER OF THE NEGATIVE FOR PLATINOTYPE.

In the earlier days of platinotype printing it was generally insisted upon that the most suitable negatives were such as we should describe as somewhat vigorous or "plucky." Whether it is that some alteration has been made in the manufacture of the paper or that taste as regards what constitutes a good print has changed, I cannot say. Certain it is that in the experience of a good many, a "plucky" negative is by no means essential to the production of a good platinotype print.

The soft, delicate negatives, of which the best professional portrait negatives are a good sample, yield the best possible results, whilst with the CC paper, negatives so thin and delicate as to be suitable for hardly any other printing process, give all that can be wished for.

Much, of course, will depend on the kind of print desired and the paper used, and here it may be remarked that from a given negative the different kinds of platinotype paper give different results.

From a given negative the hot-bath papers yield the greatest amount of half-tone, the hot development tending to yield flatter results. Next comes the smooth, cold-bath paper, and finally as yielding the maximum amount of vigour is the CC paper. Hence if we make our negatives specially for our chosen printing process, a stronger negative will be needed for S, RS, A and C than for the AA and CC, whilst for the latter a negative distinctly erring on the side of extreme thinness will be best.

If a negative gives prints which are too weak and flat for our purpose, a great improvement may be effected by printing through blue glass. If on the other hand the prints are too hard and harsh in contrast, it is advisable to print through "signal" green glass.

TONING PLATINOTYPE PRINTS.

Several formula and methods have been published from time to time, the object of which is to change the colour of the platinotype print by subsequent staining or toning, and whilst by such methods pleasing colours may sometimes be obtained, they possess an element of uncertainty, and must not be too much relied upon. An exception in this respect must, however, be made in the case of what is known as Packham's method, the effect of which is to change the black platinotype to a sepia brown, or a brown slightly tinged with green. The necessary "tinctorial powder" must be obtained from Mr. Packham or through a dealer. To prepare the bath a packet of this powder is dissolved by boiling for three or four minutes in five fluid ounces of water, to which when cold add one ounce methylated spirit. This forms the stock solution and will keep for a long time if well corked. For use add thirty or forty minims of the stock solution to one pint of water, and in this steep the prints, turning them over frequently. Toning may occupy several hours. To expedite matters, the dilute solution should be made with water of 150° F., and the bath maintained at this temperature as in the case of hot-bath development. As soon as the desired tint is secured, remove the prints and wash well in three changes of cold water.

Prints may be so treated at any time after they have been made.

Glycerine developed prints are not suitable. Prints must have been very thoroughly washed, so as to free them from every trace of acid, also thoroughly fixed in acid if they are to be "toned" by Packham's method. If after "toning" and washing the whites of the print appear to have suffered, the prints should be placed for five or ten minutes in the following bath, which should be kept at a temperature of 180° F.

Castille soap 40 grains Bicarbonate of soda 80 grains Water, hot (180° F.) 1 pint

This will clear the whites and intensify the colour generally.

Platinotypes may be toned to a red-brown by uranium nitrate, or to a bluer colour with chloride of gold. They may also be intensified by pyrogallic acid or hydroquinone, but as the purpose of this article was merely to give simple working instructions for platinotype printing for the beginner, he may defer the consideration of such side issues until he has become _au fait_ in the production of a good platinotype print.

_A. Horsley Hinton._

_Contact Printing on Bromide Paper._

It is well to bear in mind at the outset that bromide paper is extremely sensitive to light, almost as much so as is a rapid dry plate. For this reason, it is obvious that it must not be carelessly exposed to actinic light. All manipulations except the actual printing must be conducted by red or yellow light, such as is allowed to pass through glass of these colours.

For evenness of result, it is better to use a lantern than daylight, because the fluctuation in intensity of the latter is very misleading and liable to lead to failures through over or under development.

The actual colour of the light, also, is of far more importance than one would suppose: ruby light tends to give one the impression that development is complete long before that is the actual case; it is also somewhat more difficult to handle the paper satisfactorily by this light than by a good yellow.

For these and other reasons I strongly recommend the use of yellow light, a thoroughly safe one being given by gas or lamplight passing through one sheet of yellow glass and one thickness of "canary medium."

This light, while being absolutely safe, gives such perfect illumination that it is as easy to control and estimate results as it would be by ordinary unfiltered gaslight.

If a ruby glazed lantern is already in use for negative work, it can readily be prepared for bromide printing by merely removing the ruby glass and substituting the yellow and canary medium. With these brief hints as to illumination, let us consider the entire process in its various stages.

_Unpacking the Paper._--The sensitive paper is generally packed in envelopes sufficiently opaque to protect it from the admission of light. The packet must be opened in the dark-room from which _all_ light (even stray streaks beneath the door) is excluded, excepting only that given by the yellow glazed lantern. The outer envelope being carefully undone, an inner cover will be found and these wrappers should be placed on a dry table while a sheet of the paper is removed.

It is a good plan to have a "light-tight" box (obtainable from any dealer) in which to put the paper after unpacking it; this prevents loss of time and awkwardness of handling in having to replace the paper in its wrappers each time a piece is withdrawn for use.

When several prints from one or more negatives are required, it is an excellent thing to have two of these boxes, one for the unexposed paper and one in which to put the prints as made until all are ready for development.

_The Class of Negative._--Bromide paper gives us a great command over results; in fact, so vast is the control we may exercise that it is possible to secure good results from almost all classes of negatives, from mere ghosts to those with density almost equal to that of a brick wall. But there is, of course, a class of negative that gives a good result with the least expenditure of skill, such a one is generally known as of average density, having a full scale of gradation with high-lights dense, yet not so opaque as to prevent you seeing a window clearly defined when looking towards it _through_ the densest parts of the film, such as the sky, for instance. Another way to test the density is to put the negative, film side down, on some large print on white paper, the large letters should be just visible through the sky, but the smaller print should not be readable.

That is the class of negative usually considered in Instructions for Use, as an "average" negative.

_The Sensitive Side of the Paper._--A difficulty sometimes occurs in telling which is the sensitive side of the paper: this may be easily ascertained by the appearance of the edge, which turns slightly inwards _towards_ the sensitive side. This is quite apparent to the sense of touch as well as sight. Some people moisten their finger and thumb and squeeze the paper and see which sticks (the sensitive side), but that is a dirty method and quite unnecessary.

_Printing from the Negative._--Having unpacked the paper, after making sure that all but the yellow (or ruby) light has been excluded from the room, we are ready to print.

For this purpose, different workers favour different classes of light: one prefers gaslight, another swears by magnesium ribbon, and some even prefer the light of day.

Personally, I favour ordinary gaslight passed through a No. 5 Bray's burner, because it is quite rapid enough for all practical purposes and is perfectly under control and free from serious variation.

The burner should be within easy reach of the worktable and should be fitted with a byepass to obviate the necessity of continually striking matches. Several years ago I had my bromide printing rooms fitted with an excellent lantern of this class in which the byepass was connected to two jets (one inside and the other outside the lantern) in such a way as to turn down the white light with the same movement that raised the coloured light, and _vice versa_. By this means no gas was wasted and the simple action of pulling or pushing a lever operated either light at will. By placing the same lever "amidships," both jets were lowered to the point of invisibility and could so remain for days at a time, yet always ready at a moment's notice. The accompanying sketch (fig. 1) will give some idea of its construction.

If the dark-room is small, and space is an object, the sink may be fitted with a wooden cover and this may be used as a table for printing the paper, but care must be observed to avoid the slightest moisture upon it or satisfactory work is impossible and the negatives may be ruined. In a large room, it is much better to have an ordinary kitchen table removed some distance from the sink; with this and a comfortable chair bromide printing is a very pleasant occupation. The following sketch (fig. 2) will explain the arrangement of the table, and it applies equally well to the movable top of the sink.

Supposing that some arrangement of this sort is devised, we must unpack some bromide paper and put it in its box and then put a negative of "average" density in an ordinary printing frame. On the film side of the negative we must now place a sheet of bromide paper with its sensitive side in contact, replace the back of the frame and it is ready for exposure. Before exposing it, _make sure that both boxes are shut_ or their contents will be ruined the moment the white light is turned up.

Upon reference to the instructions that accompany each packet of bromide paper, you will observe a certain number of seconds' exposure is advised at a certain distance from the light; in the case of the Barnet extra rapid paper the time is given as about four seconds at a distance of eighteen inches.