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HANDBOOK OF PHOTOGRAPHY 



Xuniber 10 is a more active developer than No. 9. Developing times may be 

 expected to be 4 to 6 min. at 65°F., tray development. The developer may be mixed 

 double or triple strength as stock solution and diluted appropriately for use. 



Formulas with glycine as the reducing agent are also proposed for some classes of 

 work. They are not so commonly used as the others. One typical formula is 



No. 11 Glycine Developer 



Sodium sulphite, anhyd 25 g. 3 oz. 145 gr. 



Potassium carbonate 50 g. 6 oz. 290 gr. 



Glycine 10 g. 1 oz. 145 gr. 



Water to make 1 1. 1 gal. 



Number 11 may be expected to give normal development in 5 to 10 min. at 65°F. 

 tray development. For slower tank development it may be diluted one part of 

 developer and two parts water which will result in a development time of the order of 

 20 min. If desired, this developer may be mixed as stock solution at greater concen- 

 tration, up to five times the concentration indicated, and then diluted appropriately 

 before use. 



Process Work. — In copying line drawings or printed matter an extremely high 

 contrast between the lines and the background is desired. The emulsions made 

 particularly for this work are of contrasty type, but, to make full use of them, con- 

 trasty developing formulas are usually required. This high-contrast characteristic is 

 secured with metol-hydroquinone developers by using good concentrations of reducers 

 and high enough alkalinity to secure rapid.development. A relatively high potassium 

 bromide content is common also, to secure freedom from fog with development times 

 sufficient to come close to maximum possible contrasts. 



Table V. — Process Developers 



No. 12 



Range 



Metric 



Rhodol (metol or Elon) 



Sodium sulphite (anhydrous) 



Hydroquinone 



Sodium carbonate (monohydrated) 



Potassium bromide 



Water to 



1.0 g. 

 75.0 g. 



9.0 g. 

 30.0 g. 



5.0 g. 



1. 1. 



Avoirdupois 



58 gr. 



10 oz. 



1 oz. 87 gr. 



4 oz. 



290 gr. 



1 gal. 



Metric 



1.0- 5 g. 

 37 . 5-75 g. 



6.0-10 g. 

 22 . 5-45 g. 



3.0-12 g. 

 11. 



Avoirdupois 



58-290 gr. 



5-10 oz. 



350 gr.-l oz. 145 gr. 



33-6 oz. 

 175 gr.-l oz. 260 gr. 

 1 gal. 



Number 12 may be expected to produce good contrast in 4 to 6 min. at 65°F. 

 If less contrast is desired, one part of developer may be diluted with an equal quantity 

 of water. 



Where still greater developer activitj' is required to give maximum contrast in 

 minimum time, carbonate is no longer used for the alkali, but soda is used in its 

 place. High concentrations of both hydroquinone and bromide are typical. 



The developer is usuallj' prepared as two stock solutions, as it does not keep well 

 after mixing. A tj'pical formula is: 



No. 13 High-contrast Process Developer 



Solution A 



Hydroquinone 22 . 5 g. 3 oz. 



Sodium bisulphite 22 . 5 g. 3 oz. 



Potassium bromide 22 . 5 g. ' 3 oz. 



AVater to make 1 1. 1 gal. 



Solution B 



Sodium hydroxide 52. 5 g. 7 oz. 



Water to make 1 1. 1 gal. 



