444 HANDBOOK OF PHOTOGRAPHY 



When working with prints which are to have one of the warm colors, the correct 

 tone is still more difficult to estimate under safe-light conditions. Therefore a small 

 hulb, of perhaps 5 cp., may be used to make a quick inspection to see if the desired 

 color has been attained. 



It must be remembered that color, densitj^, and contrast are determined by the 

 developer formula and its age and temperature. 



Prints often change color in the fixing bath because, before fixation, print color is 

 controlled by the combination of black silver and of unexposed, undeveloped silver 

 halide which is light yellow. Upon fixation the unexposed emulsion disappears and 

 the shadows of the print will be blacker than before immersion in the fixing bath. 



Short Stop, Fixing, and Washing.^ — After the print is thoroughly developed, it may 

 be placed in the fixing bath, then washed and dried. An acid rinse bath may be used 

 between the developer and the fixer to stop development and to insure that the print 

 will have uniform color. The acid rinse neutralizes the alkalinity of the developer and 

 prevents the acidity of the fixer from being neutralized. It prolongs the life of the 

 fixing bath. Prints may be kept in the rinse bath until all are ready, and then all put 

 through the fixing bath at once. 



Prints should be left in a fresh fixing bath for about 15 min. It is most important 

 that their position should be changed frequently. Prints matted together and left 

 stagnant in the bath will lack permanence. Best results are secured by the use of two 

 baths, one partially exhausted for preliminarj^ fixing, and one made up fresh for final 

 fixation. 



The acid rinse between developer and fixer will aid materially in prolonging the 

 usefulness of the fixing bath. For example, the Eastman Kodak F-1 fixing solution 

 will treat 120, 8- by 10-in. prints per gallon when the SB-1 rinse is used; but only half 

 this number without the stop bath. 



Washing is equally as important as any part of the printing process. The general 

 tendency to throw the prints in a tray or stagnant pool of water and to stir them up 

 occasionally is not satisfactory. Prints should be run through numerous changes of 

 water, and the order of prints from top to bottom of the pile should be changed 

 occasionally. Prints on heavy supports require longer washing periods than single- 

 weight papers. 



Short Stop (Eastman SB-1) 



Water 32 oz. 11. 



Acetic acid (28 per cent) IH oz. 48 cc. 



This is sufficient for 100, SJ-^ by oJ-^-in. prints. 



Acid Hardening Fixing Bath 

 (Eastman F-1 and Defender 2-F) 



Water 64 oz. 2 1. 



Hypo 16 oz. 480 g. 



When completely dissolved add 



Water (about 125° F.) (52° C.) 5 oz. 160 cc. 



Sodium Sulphite (desiccated) 1 oz. 30 g. 



Acetic Acid (28 per cent pure) ' 3 oz. 96 cc. 



Potassium Alum 1 oz. 30 g. 



' To make 28 per cent acetic acid from glacial acetic acid, dilute 3 parts glacial acid with 8 

 parts water. 



To mix the hardener, dissolve the chemicals in the order given. The sulphite 

 should be dissolved completely before adding the acetic acid. After the sulphite- 

 acid solution has been mixed thoroughly, add the potassium alum with constant stir- 

 ring. Cool the hardener, and add it slowlj^ to the cool hypo solution while stirring 

 the latter rapidly. 



1 See aso Chapter on Fixing, Washing, and Drying. 



