THE above heading has no reference to temperance drinks, but is the universal abbreviation used in describing a particular method of photographic printing. I suppose there is scarcely any need to explain that the strenuous life of the late nineteenth and early twentieth-century periods has compelled photographers (and who does not photograph nowadays?) to adopt this as a convenient abbreviation to the proper name, viz. Printing-out-Papers. True, I know one amateur who probably uses this method far more than any other, and who always speaks of it with a loving intonation in his voice as if the term carried some occult meaning with it. He invariably says "pop-papers," so I presume he does not realise the exact meaning. To many minds the term " P.O.P." has somehow or other received a peculiar limitation. When they ask for P.O.P. they mean gelatino-chloride of silver emulsion paper, and no other. This limitation is becoming almost universal now, irrespective of the fact that albumino-chloride and collodio-chlorideare also printing-out-papers. So for the purposes of this article I propose to stick to the P.O.P.-ular idea rather than a scientifically correct rendering, and shall therefore deal with the well-known gelatine emulsion papers only.

It has been said times without number that the advent of the dry-plate inaugurated the reign of the ubiquitous amateur in photography. Doubtless ! But I venture to add to that the statement that the dry plate alone could never have accomplished it, and that P.O.P. had as large an influence in making easy and popularising photography as ever the dry plate had. And this is queer, because P.O.P. is not the easiest process to work after all is said and done. There are so many ways of spoiling a batch of prints that one often wonders why the beginner does not tackle bromide paper or gaslight paper first. The reason undoubtedly is that one can see what one is doing with P.O.P., and that does away with the feeling of blind guesswork that attaches to one's first attempts with development papers. However, P.O.P., with its visible image, certainly holds the field among beginners, and the consideration of a few pointers in producing good results with certainty should be acceptable.

The instruction sheets issued by the manufacturers of Barnet P.O.P. say :—

Care should be taken—(1) to keep the prints moving in the different solutions ; (2) to keep separate dishes for working P.O.P., and never use them for any other purpose ; (3) to use only the best chemicals; and (4) to be scrupulously clean in all operations. To these points may be added one or two others, equally important—e.g. to keep the papei in good condition before, during, and after printing, previous to toning; to keep all solutions at an equable temperature; and to carry rules (2) and (4) to a greater refinement by keeping each dish for its own particular use (washing, toning, or fixing); and by regarding the necessity for chemical cleanliness to apply to the manipulator's hands and fingers just as much as it does to dishes and measures.

Taking these points seriatim, the need for constant movement of the prints is a very real need, because unless the various solutions have free and equal access to all parts of the prints—front and back—at the same time unequal chemical action is inevitable, and hence patchy, unequally-toned prints, or else imperfectly fixed or washed prints, which will ultimately discolour in patches. The method of moving the prints is worth mentioning. Many workers seem to think that if the dish is kept rocking, as in developing a plate, it is sufficient. Far from it. Such a plan might answer for single prints, but not for batches. The correct way is to feed the prints separately into the bath, each one face downwards. This is done with the right hand whilst keeping the mass of prints on the move with the left hand. Thus each hand is kept in a different solution, and never touches the other until the whole batch is transferred. Both hands can then be used in the one bath, and the whole batch kept constantly on the move by inserting the fingers under the prints and continually bringing the bottom ones up to the top. This can be done singly in the case of small batches of a dozen or fifteen prints ; but larger batches need quicker attention, and the bottom ones should be withdrawn in lots of three or four at a time with the right hand. They are then quickly separated with the left hand, whilst the right is fishing for another lot. The advisability of keeping each hand in its own dish is most plainly seen when hypo is one of the solutions in use; but the method still holds good in the case of other solutions, which do not show the evil effects of contamination so unmistakably. Besides which it is a good habit to cultivate until it becomes automatic.

The second point should not need elaboration ; it is self-evident. Dishes can now be obtained which are legibly marked " washing," " toning " and " fixing," and each dish should be religiously kept for its own particular purpose.



The third point should also be axiomatic. It applies to all chemicals used, but most emphatically to the gold. Cheap gold cannot be good, because gold is gold the world over, and any attempt at cutting the already phenomenally low price of gold chloride can only result in a diminution of the quantity of the precious metal present in the salt—to the detriment of results. I suggest that for the occasional worker Burroughs & Wellcome's tabloid toning baths are probably the neatest and best way of compounding the baths, and the purity of the chemicals is guaranteed by the firm putting them up.

Allied to this point is the use of hypo for more than one batch of prints. This is a most heinous offence for a silver printer to commit. There can be no excuse either. Hypo at 2d. per lb. is "cheap enough to eat," and whilst two pennyworth of hypo will make over half a gallon of fixing bath it is false economy to attempt a second use of it, although it may apparently work all right.

Clean dishes and measures are easily attained. A small stiff brush and a little Monkey Brand soap, plus elbow-grease, will do the trick. But I have seen printers who would spend a quarter of an hour scrubbing their dishes out, and who yet would have the impudence (I can call it nothing else) to eat apples or oranges whilst attending to their printing frames. Naturally, the result was red patches (where the fingers had touched the paper), which refused to tone, and the poor paper manufacturer was blamed because the printer was "quite sure his dishes were clean." Another way in which one may unconsciously sin. Many persons are liable to an imperceptible perspiration in the hands and finger-tips of which they are unaware. To this exudation P.O.P. is extremely sensitive, and the effect is much the same as that caused by greasy fingers. A simple remedy is to wash the hands in borax and water before handling P.O.P.