464 HANDBOOK OF PHOTOGRAPHY 



Dye 0.2 g. 3 gr. 



Acetic acid (10 per cent) 5 cc. 75 minims 



Water 1 1. 35 oz. 



The dye is dissolved in hot water and filtered. The acid is then added, together 

 with cold water to make up the required bulk. The positives are left in the dye 

 solution until the desired tone is obtained and then washed until the excess dye is 

 removed from the lighter areas of the picture. 



A partial list of basic dyes suitable for dye toning is the following : 



Rhodamine G Red 



Auramine Orange 



Chrysoidiue Yellow- 

 Malachite Green Green 



Methylene Blue Blue 



Methyl Violet Violet 



When working with paper prints, the dye is usually held by the fibers and baryta 

 coat of the paper base to quite a great extent, but sometimes a large part of this excess 

 dyeing may be removed by washing with water. Finallj^ any objectionable coloring 

 of the whites or high lights may be removed from the dried print by immersing in the 

 following clearing solution for from 1 to 2 min. : 



Potassium permanganate i g. 3}'2 gr. 



Sulphuric acid 1>2 cc. 20 minims 



Water to 1 1. 20 oz. 



Another mordanting bath is one which is described in the British Journal and 

 Almanac for 1927: 



Copper sulphate 40 g 



Tribasic potassium citrate 60 g 



Glacial acetic acid 30 g 



Potassium or ammonium sulphocyanide 20 g 



Water 1 1 



350 gr. 

 524 gr. 

 262 gr. 

 175 gr. 

 20 oz. 



The print is mordanted for from 1 to 15 min., washed for about 30 min., laid out 

 on a sheet of glass and surface dried. A 10 per cent solution of the dyes or mixture 

 of dyes, and 1 per cent acetic acid is then applied with a tuft of cotton or flat brush. 



Crabtree and Ives have described a method of dye toning with a single solution, 

 which, although intended for toning motion-picture films, may also be used with a 

 certain measure of success on some papers. Here the dye is mixed with the mordant- 

 ing solution in a concentration of from 0.02 per cent to 0.04 per cent, and sometimes 

 higher, depending on the kind of dye used. The combined mordanting and dye 

 formulas follows: 



Dye (to make a final concentration of 0.02 to 0.04 per cent 



depending on the kind of dye) X g. 



Acetone 100 cc. 



Potassium ferricyanide 1 g. 



Acetic acid (glacial) 5 cc. 



Water to make 11. 32 oz. 



The dye should be dissolved completely in a small volume of hot water, and added, 

 with stirring, to the acetone. This mixture is then immediately diluted to about 

 three-fourths the final volume with cold water. The potassium ferricyanide is dis- 

 solved in a small volume of water, and the acetic acid added. This mixture is added 

 to the dye solution with constant stirring, and the whole diluted to the final volume 

 for use. 



Some experimental work will have to be done in order to determine the proper 

 concentration of dye in the solution before serious work is attempted. As a rule 



