When all the detail has appeared it may still appear lacking in vigour and contrast, but this will come if sufficient time be allowed. _Development should not be stopped until the print is of the full strength required_, but it is not advisable to allow it to become much darker than it is desired to appear when finished, because there is very little loss of strength in the fixing bath.
If the image flashes out immediately upon the application of the developer, the paper has been over-exposed. A strong dose (one or two drams) of ten per cent. bromide added to the developer may help to save it, but the enlargement will probably look poor and flat and of bad colour when finished. If the picture appears very slowly, and refuses to gain in strength, under-exposure is the cause, and two or three drams of a ten per cent. solution of sulphite of soda may improve matters, but as a rule the most satisfactory plan will be to make another exposure. With regard to the strength of the developer, that given is very suitable for negatives of normal density, but some papers may require a little more amidol, the appearance of the finished enlargements will guide the reader in regulating the quant.i.ty to suit the particular paper with which he may be working.
The enlargement should be washed in plenty of running water from the tap to arrest development, and then fixed in:--
Hyposulphite of soda 4 ounces.
Water 20 "
A quarter of an hour should be allowed for fixation, but it is better to use two baths, giving ten minutes in each. After washing in running water for a couple of hours they may be hung up by one corner to dry, or pinned down to a blotting board.
Enlargements produced in the manner described should be of a pure engraving black colour, and if they are mounted upon _pure_ boards with _freshly_ made Glenfield starch, they should prove permanent.
Enlargements are frequently toned to various shades of brown and red, generally by the employment of the uranium-toning bath.
Although the colours so obtained are often very artistic and pleasing, no reliance can be placed upon the permanence of an enlargement so treated, and the writer strongly recommends that when warm coloured prints are desired, an enlarged negative should be made and prints made therefrom in carbon, silver, or sepia platinotype.
ENLARGED NEGATIVES.
The production of an enlarged negative presents no difficulty that need deter any careful worker from attempting the work. No additional apparatus to that already described will be required, and either day or artificial light may be employed. In the first place a transparency must be made from the small original negative. It may be made either by contact or in the camera, preferably the latter as then the acme of sharpness will be obtained. If, however, the reader is acquainted with the carbon process he cannot do better than make a carbon transparency, for such are specially adapted for the production of enlarged negatives. Many, however, will prefer to make the transparency on a bromide plate, and as this is the part of the process which requires the greatest amount of care, and as _in fact_ the _quality of the enlarged negative will entirely depend upon the character of the small transparency_, it is necessary to deal with the matter somewhat in detail. Preconceived ideas of quality based upon the appearance of a good lantern slide must be put aside, for that is not at all what is required. What is wanted is a transparency in which every possible detail existing in the negative has been reproduced, and which in comparison with a lantern slide would look rather flat and over-exposed. Every possible precaution should be taken to avoid granularity or coa.r.s.eness of image, therefore a slow plate is almost essential; plates coated with lantern-slide emulsion are now obtainable, and will be found very suitable. A full exposure should be given, and a weak and well-restrained developer employed. These conditions tend to the production of the qualities desired. Warm coloured transparencies so produced generally have a finer grain than those developed to a black or colder colour, but unless the colours produced are fairly uniform, considerable variation in exposure when making the enlarged negatives will be necessary, and for this reason it would perhaps be better for the beginner to aim at the production of good black transparencies possessing the qualities indicated.
The small transparency, having been fixed, washed and dried, should be edged with black paper to prevent any subsequent fogging of the plate, by the lateral spreading action of the light. It is then placed in the enlarging apparatus, just as in the case of a negative, and carefully focussed. This operation must be very carefully performed. The writer uses a thin and very sharp negative of an architectural subject to focus with, afterwards subst.i.tuting the transparency which is to be enlarged. Landscape subjects, consisting chiefly of foliage, are seldom critically sharp, and it is then difficult to secure a sharply-focussed enlargement. The remainder of the operation is extremely simple. In the place of the ground-gla.s.s screen (which in this case should have its rough or ground side nearest to the enlarging lens) a slow dry plate is placed, backed with a piece of cardboard covered with black velvet to avoid reflections and possible fog. The exposure should be full, and a weak developer employed. Trial exposures may be made on quarter-plates, coated from the same batch of emulsion, which the manufacturers will willingly supply, if the purpose for which they are required is made known. Pyro will be found the most suitable developer, but it should contain a full proportion of sulphite, and not be too strong. Exposure and development should be so adjusted that by the time every possible detail has been developed up, the plate will not have become unduly dense. If expense has to be considered, a piece of slow smooth bromide paper may be subst.i.tuted for the large dry plate in which case the result will be an enlarged paper negative. For large sizes, 15 12 and beyond, the latter is a very economical method of working, and the negatives will be found to yield most artistic prints, and if the operations have been carried out as described, and the prescribed conditions carefully observed, the grain of the paper will not show obtrusively or unpleasantly in the prints.
An alternative method of working, and one which admits of a large amount of control over the ultimate result, is to make in the first place a large transparency of the full size that the enlarged negative is desired to be. All the precautions upon which stress has been laid should be observed in regard to the choice of plate, developer, etc.; but in this case the enlarged transparency may be given a little more vigour and sparkle than would be desirable if the other method of reproduction were adopted, though in this the reader must be guided by the particular effect which he may be seeking to produce in his prints. For this purpose pyro will be found to be the most suitable developer, in that it permits of a large amount of control. From the large transparency a negative is produced by contact printing either upon a plate, or upon a piece of bromide paper.
The great advantages of the latter mode of working are the facilities which are afforded for retouching or working upon the large transparency. Negative retouching is always a difficult operation to an amateur, for he cannot see the effect of his work until he has made a print; whereas, in retouching a transparency the effect produced by each stroke of the pencil or brush is at once apparent. In the s.p.a.ce at disposal it is not possible to describe the various ways in which improvements can be effected. First there are the chemical aids of local intensification or reduction. Then much may be done by the judicious use of a pencil, but the part to be retouched must first be lightly rubbed with a little retouching medium in order to make the pencil bite. In extreme cases the back of the negative may be covered with tissue paper upon which a stump and chalk may be used _at discretion_.
The novice must not be disappointed with the appearance of his enlarged negative when it is finished, nor should he form an adverse opinion of its printing qualities until he has made a print from it.
Confessedly an enlarged negative generally presents a different appearance to one that has been taken direct, and may even seem to lack some of those qualities that are commonly regarded as essential to perfection, but if the final result, the picture, comes up to our expectations, we may surely dismiss any lingering doubts as to whether the enlarged negative conforms to certain preconceived notions of technique, and it should be enough for us to know (and the fact is incontrovertible) that some of the finest and most artistic photographs ever shown owe their existence to this method of production.
_John A. Hodges._
[Ill.u.s.tration: Walberswick. By Rev. A. H. Blake.]
_P.O.P._
[Ill.u.s.tration]
The three letters "P.O.P." are now so widely understood as referring to the Gelatino-Chloride Printing-Out cla.s.s of Papers that it may be said that P.O.P. is known to many who are not acquainted with the fully-written name of this cla.s.s of productions.
Also it should be mentioned that when these papers are spoken of as gelatino-chloride papers it is not to be concluded therefrom that chloride of silver is the only silver salt present. What they do actually contain is probably only known to their respective producers. But generally speaking, it is enough to say that so far as the ordinary consumer is concerned, the family resemblance is so strong and chief characteristics so general that the following directions for using them may be held as generally applicable to the various well-known brands now on the market. At the outset, however, it will be convenient to note that for the purposes of manipulation we may roughly group them into two chief cla.s.ses--_viz._, the matt (probably from the German word "matt," _i.e._, dull) and the glazed, glossy or enamelled. The latter comes to us with a highly glazed, _i.e._, shiny smooth surface, the former being slightly rough, of a surface and texture somewhat like that of very finely ground gla.s.s.
_Care of the Paper._--The paper is sent out either in the full-sized sheet, measuring about 24 17 inches, or in smaller cut sizes, suitable for the usual 1/4, 1/2, 1/1 plate and other popular dimensions of plates. Compared with alb.u.menized print-out paper, P.O.P. is more sensitive to light; therefore, some care must be taken to avoid needlessly exposing it to the influence of daylight or strong artificial light. For example, the printing frames should be filled as far away from any window as possible, and the prints examined from time to time either by gaslight or as feeble daylight as possible.
In handling the paper--cutting it up, etc.--care must be taken to avoid touching the sensitive surface with the fingers in any case.
The touch of a moist or hot finger is very likely to produce a mark or stain which is usually irremovable. The paper should be protected from damp, excessive heat and impure air. If kept _rolled_ in a tin tube or _flat_ under pressure in the original packages, it will keep a considerable time--_i.e._, longer than ordinary alb.u.menized paper.
_Printing_ is done in the usual way. Strong diffused light reflected from the sky or clouds usually gives a better print than direct sunshine. In case, however, of a thin flat negative--_i.e._, one with insufficient contrast--good results may sometimes be obtained by covering the printing frame with a sheet of green gla.s.s and printing in moderately strong sunshine. In hot summer sunshine it is as well to cover the green gla.s.s with a sheet of tissue paper or fine-ground gla.s.s. Care must be always taken when printing in sunshine or very hot weather to see that the negative itself does not get too warm, or the paper may stick to it. In this case the print is of course lost, and the negative, unless varnished, is also probably seriously damaged by silver stains, which are very difficult to remove. Printing should not be carried quite so far as in the case of ordinary alb.u.menized paper because in the subsequent operations of toning, etc., not so much strength is lost. The same care as regards shielding from light, etc., should be given to the prints after they leave the printing frame. They may be proceeded with at once or kept for some days before being toned, etc., but if this is done the prints should be kept under pressure. Some workers have thought that the light action goes on, "continues" in the print after it is removed from the printing frame. This, however, is not the generally received opinion.
_Washing._--It is important that the first washing should be done 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 pa.s.s 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 pa.s.sed 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 gla.s.s 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.