468 HANDBOOK OF PHOTOGRAPHY 



Solution A 



Water, cool 350 cc. 12 oz. 



Gelatin 12.0 g. 180 gr. 



Cooking gelatin may be used, but Nelson's No. 1 Hard is preferable. Allow the 

 gelatin to soak until it is thoroughly swollen, then melt in a double boiler. 



Solution B 



Water, hot 60 cc. 2 oz. 



Chrome alum 2 . 5 g. 36 gr. 



Pour B into A slowly, with constant stirring. The solution must be used hot. 



It is most convenient to prepare the paper in large sheets, later cutting it to size. 

 Pin a sheet down on a flat surface, wet a small sponge in water as hot as the hand can 

 bear, squeeze it out, and take up with it a small amount of the hot gelatin solution. 

 Rub this over the surface of the paper, scrubbing it well into the pores, then hang the 

 paper up to dry. Do the same with several other sheets, giving each one a second coat 

 as soon as the first is dry. It is impossible to say definitely how many applications 

 will be necessary; a very rough paper, such as a Whatman Cold Pressed Rough, or a 

 very soft paper, may require as many as five; on the other hand, a hard or a smooth 

 paper may not need more than two; only experience can tell the precise amount of 

 gelatin necessary. 



When dry, the transfer paper may be cut to size and stored; the chrome alum 

 renders it less liable to the attacks of bacteria than is the tissue. It should be cut 

 rather larger than the print is to be, say 9 by 11 or 10 by 12 for an 8- by 10-in. print, 

 and it is well to mark the back with pencil, since the coated side cannot be distin- 

 guished from the uncoated when it is wet. 



Sensitizing. — Many different formulas have been suggested for sensitizing the 

 tissue, the best with which the writer is acquainted being the following, which was 

 suggested and worked out by Kirtland Flynn and A. K. Aster, members of the Orange 

 Camera Club. 



Water, distilled 1000.0 cc. 30 oz. 



Potassium chromate 30 . g. 440 gr. 



Citric acid as much as suffices to neutralize the solution (about 22 gr.) will be required. 



This sensitizer gives a film which behaves verj^ nicely during development, and 

 appears to hold gradation in the high lights better than any other that has yet been 

 worked out. 



The sensitizer keeps indefinitely and may be used repeatedly if stored in a brown 

 bottle or otherwise kept from the light and if filtered back into the bottle after use. 

 Sensitizing may be done in an ordinary room, since the tissue is not sensitive to light 

 until dry. The sensitizer should be used at a temperature between 65 and 70°F.; 

 it can be used warmer, but if it is too warm the gelatin may be softened excessively. 



To sensitize, pour the solution to a depth of % in. or more into a clean tray, take 

 the carbon tissue by the edges and immerse it, face up, in the solution. The tissue 

 will tend to curl, coated side in, and should be pressed down under the surface. After 

 about a minute it will lie flat, when it should be turned over, and any adhering bubbles 

 should be brushed from the back. Any bubbles which may have adhered to the 

 coated side should, of course, be broken by a light touch of the finger as soon as they 

 appear. The tissue is now turned face up, and the tray is rocked, keeping the tissue 

 under the surface of the solution, until a total time of 2,V2 min. from the first immersion 

 has elapsed. It is then lifted by two corners, drained for a few seconds, and laid face 

 down on a clean sheet of glass, being lightly squeegeed on the back to remove the 

 excess of sensitizer, when it is stripped off and hung up in the dark to dry. 



