484 HANDBOOK OF PHOTOGRAPHY 



It will very likely be found that the first processing has removed the size from the 

 paper to such an extent that it must be resized before the second sensitizer is applied; 

 also, some papers will require sizing before the first sensitizing. The operation of 

 sizing may be carried out as follows: 



Sizing. — Make up the following solutions: 



Solution A 



Water, cool 350.0 cc. 12 oz. 



Gelatin 12.0 g. 180 gr. 



Cooking gelatin is perfectly satisfactory. Allow the gelatin to soak until well 

 swollen, then melt in a double boiler. 



Solution B 



Water, hot 60.0 cc. 2 oz. 



Chrome alum 2 . 5 g. 36 gr. 



Pour B into A while both are hot, stirring constantly. Pour the hot solution into a 

 tray, and immerse the print or paper in it, allowing it to remain until well soaked, then 

 hang it up to dry. There will undoubtedly be bubbles on the surface of the paper, 

 but these may be removed by drawing the paper over the edge of the tray when taking 

 it from the size or by wiping the surface with a glass stirring rod or a soft automobile 

 windshield-wiper blade. 



It may be found that this gives a heavier sizing than is desired, in which case the 

 size may be diluted with hot water to the desired point. The size should be kept 

 warm when in use, and after sizing one batch of paper or prints, it should be thrown 

 away, as it does not work well if allowed to cool. 



Brush Development. — If local modification of values is desired, the only way it can 

 be attained is by brush development with glycerin. The materials required are : two 

 or three soft camel's-hair brushes of different sizes; a supply — 16 oz. or so — of glycerin; 

 a sheet of glass somewhat larger than the print; developer; three small receptacles, 

 such as 1- or 2-oz. graduates; and a plentiful supply of clean hard-surfaced blotters. 

 The print should be timed much more fully than normal. A layer of glycerin having 

 been placed on the glass, the print is plastered down on this. A rather thick coat of 

 glycerin is then painted over the surface of the print; the graduates are filled— one 

 with clear developer, one with a mixture of equal parts of developer and glycerin, and 

 one with clear glycerin. The various areas of the print are then developed by brushing 

 one or another of the solutions over the surface, as required, and blotting freely from 

 time to time. The function of the glycerin is to retard development and give oppor- 

 tunity for what local bringing up of values may be desired. When the operation has 

 gone to the desired point, the print is cleared and washed as usual, the final operation 

 being generally to place the finished print face down in the ash can. It will be apparent 

 that the desirability of the results depends almost entirely on the worker's manual 

 dexterity and his appreciation of the tonal relationships necessary to produce a satis- 

 factory picture, this latter point being one in which most amateur photographers (and 

 professionals also) are notably weak. However, it must be admitted that very fine 

 pictures have been produced by this method. 



Gum Platinum. — If it is desired to increase the depth and richness of the shadows in 

 a platinum print, the finished print may be given a coating of a gum-pigment mixture, 

 as described in the section on Gum Printing. This gum coating • is printed and 

 developed in the usual manner. This treatment often adds tremendously' to the 

 appearance of the final print, though it destroys the characteristic surface texture of 

 the platinum paper. It is almost invariably necessary to size the paper before apply- 

 ing the gum coating, and it will probably be found that a more dilute size than that 



