COLOR PHOTOGRAPHY 633 



Stock Solution BB 



Stock solution B 1 part 



Water (distilled) 2 parts 



Working Bath 



Water . 20>2 oz. 



Stock solution A 3 oz. 



Stock solution BB 11 dram 



The above Type II single-bath formula and the compounding of the working bath 

 have been highly recommended in the past by outstanding color workers. With this 

 proportion of chemicals, however, the deep shadows of the image in the bromide do not 

 completely bleach out, and there is danger of losing proportionality. On the basis of 

 very careful investigations it has been found desirable to increase the amount of 

 bleaching chemicals in the working bath. 



The following is a very dependable working bath : 



Working Solution Ml 



Water 19% oz. 



Stock solution A 4 oz. 



Stock solution BB 1 1 H dram 



With the single-bath method, irrespective of the type of solution adopted, each 

 tissue should be immersed in water for 3 min., drained for 15 or 20 sec, and then 

 immersed in the carbro solution for about 45 sec; after this it is squeegeed onto the 

 appropriate bromide without draining and left in contact for 10 or 15 min. 



The single-bath method with the Type II solution is to be preferred over any other 

 because, although not as critical as the double-bath method, it offers nevertheless an 

 appreciable amount of control, by increasing or decreasing the length of time of 

 immersion in the carbro bath. The preliminary water bath for 3 min. must not be 

 reduced, otherwise irregularities might result. 



It is important also to note that the contrast increases with successive tissues owing 

 to the fact that the consumption of acid is greater than that of bleaching chemicals. 



This effect could be made use of by treating the tissues in the sequence : magenta, 

 yellow, and blue-green because, as it will be seen shortly, the magenta tissue should be 

 the least contrasty of all. 



Greater flexibility of control, however, can be best obtained by mixing up the 

 carbro solution in sufficiently large quantity, dividing it in three parts and using one 

 part for each tissue. 



A convenient amount for an 11- by 14-in. set would be (Type II) 



Working Solution M2 



Water 59 oz. 



Stock solution A 12 oz. 



Stock solution BB 4H oz. 



For use take approximately 25 oz. for each tissue. For larger or smaller tissues 

 the quantity of solution should be proportional to the ratio of the tissue area as com- 

 pared with the 11- by 14-in. set. 



Since the area of an 11- by 14-in. tissue is 154 sq. in., an 8- by 10-in. tissue measur- 

 ing 80 sq. in. would require 154/80 = 1.93 less solution or 25/1.93 = 13 oz.; hence a 

 total quantity of 39 oz. of working bath should be made up if dealing with an 8- by 

 10-in. set. 



If the above quantity is considered too large for 11- by 14-in. tissues, a total amount 

 of 45 oz. of working bath can be made up using 15 oz. for each tissue. 



It must be pointed out, however, that a smaller quantity of solution for a given 

 area increases the contrast, and therefore the stock solution BB must be slightly 

 increased. 



