046 handbook of photography 



Formula 3 — Vigorous Developer for Good Prints from Soft Negatives 



Solution A 



Water 32 oz. 1000 cc. 



Hydroquinone 1 . 5 oz. 45 g. 



Sodium sulphite (dry) 1 oz. 30 g. 



Sulphuric acid 60 minims 4 oc. 



Solution B 



Water 32 oz. 1000 cc. 



Sodium carbonate (dry) 4 oz. 130 g. 



Potassium bromide 120 gr. 8 g. 



Sodium sulphite (dry) 3 oz. 90 g. 



Use equal parts of solutions A and B and develop 5 min. at 70°F. 



Assuming that the negatives are carefully balanced or that a satisfactory measure- 

 ment of the factor of the three negatives has been determined with a densitometer, an 

 additional factor with respect to the three chromatic colors is necessary. A satisfac- 

 tory print from the green-filter negative is first obtained. The exposure necessary for 

 the print from the red-filter negative must be increased 10 per cent and the exposure 

 of the print from the blue-filter negative by 25 per cent over the exposure given to the 

 green-filter negative. After development with the appropriate developer, the three 

 positives are fiixed in an acid fixing bath. The Eastman F-5 fixing-bath formula is 

 satisfactory for this purpose. The washing of the positive prints must be carried out 

 for at least 15 min. in running water to make sure that every trace of hypo has been 

 removed, otherwise the subsequent chemical operation might be badly affected. The 

 manufacturers of the Chromatone material recommend the following thiocj'^anate 

 fixing bath whenever speed is necessary, as even a trace of this chemical does not 

 interfere with the toning solutions if the washing is not carried out fully: 



Water 1000 cc. 



Potassium thiocyanate 100 g. 



Potassium alum 50 g. 



Glacial acetic acid 25 cc. 



During the process of washing, the collodion emulsion ordinarily detaches from 

 the paper base, and it must be carefully handled to avoid tearing. 



Before proceeding with the toning operations, the following miscellaneous solutions 

 must be made up: 



Solution A — Dilute Hydrochloric Acid 



Hydrochloric acid (c.p.) 16 oz. 500 cc. 



Distilled water 48 oz. 1500 cc. 



Solution B — Standard Hypo Solution 



Granular or rice hypo 2,V4 oz. 70 g. 



Distilled water 32 oz. 1000 cc. 



Wherever the text refers to standard hypo sohdion this is the formula that must be 

 used. A bath containing acid or alum will bring complete failure. 



Solution C — Standard Ferricyanide Solution 



Potassium ferricyanide i-i oz. 1 1 g. 



Distilled water 4 oz. 100 cc. 



Working Solutions for Chromatone Color Prints 



(Sufficient Quantity for Toning 5- by 7-In. Prints) 

 Red and Blue Toner A Working Solution 



Water 1 oz. 25 cc. 



Red and blue toner A 1 oz. 25 cc. 



Standard ferricyanide solution 13-5 drams 5 cc. 



This solution does not keep well when mixed, and only sufficient should be prepared 

 for prints in process. 



