TIIE ALPHA PAPER. AND THE ALPIIA OPAL PLATES.
We by no means wish to take up the business of prophesying what may or what may not be the future of photographic printing ; but we will venture to say that in the Alpha paper, which has been brought before the public since the first edition of this work was published, albumenised paper will have a formidable rival, and that for certain purposes at any rate the use of " Alpha " paper will entirely supersede that of albumenised paper.
Prints produced on Alpha paper can scarcely be dis tinguished from those on albumenised paper, whilst the new process has the following decided advantages : First. The time required for expoSure, instead of being from perhaps a quarter of an hour to several days, accord ing to the nature of the negative and the condition of the weather, is but a second or two when daylight is in question, only a minute or two even with gaslight or lamplight.
Second. There is every reason to believe that the prints on Alpha paper are more permanent than those on sensitised albumenised paper.
Concerning the matter of the reduction of exposure, it is scarcely necessary to point out how advantageous it may be in many circumstances. Notably it will make the paper useful where it is desired to produce a number of impressions from a negative in a short space of time. Possibly the amateur will feel the benefit of the intro duction of the new paper more than any other. It is generally in the printing that he gets bothered ; it is so slow a process with the ordinary paper. Then the amateur is often engaged in business during the daytime —the only time when printing on albumenised paper is possible. His few holidays he likes to spend with the camera in the field, and, as a result, he often takes negatives from which he never gets a print, or he sends his negatives away from home to be printed from by a professional photographer. With the Alpha paper he will be able, with an ordinary gas-burner or lamp, to produce as many prints in an hour as he could on albumenised paper in a clay.
As to permanency, of course nothing absolute can be said at present,—time alone can prove this. But it is the general opinion of experts that the prints are at least far more lasting than those on albumenised paper.
As we state this with considerable confidence we ought to give our reasons.
There can be no doubt that in the case of prints on albumenised paper, at least one cause of the deteriora tion which takes place through time—the chief cause, in the writer's opinion—is the organic compound pro duced by the action of the excess of nitrate of silver on the organic materials in and on the paper. An organic compound is formed,—albumenate of silver we are told, —and this compound gives rise to an unstable image. Now during no part of the manufacture of the Alpha paper is free silver nitrate brought into contact with any organic substance. For this reason the organic compound of silver already mentioned cannot exist in the paper.
Briefly stated the method of working is as follows : Alpha paper is placed in a printing frame in the usual manner, manipulations being performed in the dark room, or, still better, in a room lighted with a good amount of red or yellow light.
The paper is now exposed to light. There will be no visible image with the correct exposure unless the nega tive is a very dense one, when the deepest shadows will be faintly visible.
The paper is developed, an operation which takes less than a minute.
It is then washed, treated for a quarter of an hour with alum solution, washed for a few minutes again, toned in the usual manner, then fixed.
It is necessary to go somewhat more minutely into a description of these various processes.
The length of exposure necessary will, of course, vary with the nature of the light and with the negative.
With a negative of average density, and a distance of six or eight inches from an ordinary fish-tail burner, the exposure will be two to four minutes. By the use of an " albo carbon " light and a tin reflector the exposure may be reduced from ten seconds to half a minute. In bright summer diffused light the exposure may be about as brief as can be given. Certainly under a second will do. The exposure to bright sunshine is too brief to be under command, except in the case of negatives of extraordinary density.