TECHNIQUE OF DEVELOPMENT 



367 



No. 8 Metol-pyro Developer 



Stock Solution, A 



Metol 7 . 6 g. 



Sodium bisulphite 7 . 5 g. 



Pyro 30 . g. 



Potassium bromide 4 . 2 g. 



Water to 1.01. 



Stock Solution B 



Sodium sulphite (anhydrous) 150 g 



Water to 11. 



Stock Solution C 



Sodium carbonate (moiiohydrated) 90.0 g. 



Water to 1.01. 



Control of the development characteristics may be exercised through the dilution 

 used in making the developer from these stock solutions. One part of each, A, B, 

 and C diluted with 8 parts of water for tray development and with 13 parts of water 

 for tank development has been recommended. Developing times with normal nega- 

 tive materials will often lie between 7 to 9 min. at 65°F. for the tray developments and 

 between 9 and 12 min. at 65°F. at the tank dilution. 



Borax developers used in portrait and commercial work are the same type as the 

 more concentrated of the formulas used for motion-picture negatives. The more 

 dilute formulas may also be used, but under the conditions of low agitation usually 

 encountered in this type of work the developing times become too long to be practical. 



Metol, hydroquinone, carbonate developers are also used for these types of work. 

 Great control of contrast characteristics can be obtained with these basic ingredients. 

 Usually the rather soft working formulas are desired. These are obtained by using 

 dilute formulas or lowering the pH by reduction in the carbonate or use of bisulphite as 

 part of the preservative. The latter method is sometimes preferred when long life 

 is desired, as the desired contrast characteristics can be thus combined with sufficient 

 concentration to give good life. 



Table IV. — Metol, Hydroquinone, Carbonate Developers 



Rhodol (metol or Elon) , . . . 



Sodium sulphite (anhy- 

 drous) 



Sodium bisulphite . 



Hydroquinone 



Sodium carbonate (mono- 

 hydrated) 



Potassium bromide 



Water to make 



No. 9 



Metric 



1.5 g. 



45.0 g. 

 1.0 g. 

 3.0 g. 



6.0 g. 

 0.80 g. 

 1.01. 



Avoir- 

 dupois 



88 gr. 



6 oz. 



58 gr. 



176 gr. 



3.50 gr. 



47 gr. 



1 gal 



No. 10 



Metric 



1.0 g. 



15.0 g. 



4.0 g. 



26.5 g. 

 0.60 g. 

 1.0 1. 



Avoirdupois 



58 gr. 



2 oz. 



232 gr. 



3 oz. 232 gr. 

 35 gr. 

 1 gal. 



Range 



Metric 



0.75- 1.5 g. 



15.0 -45.0 g. 

 - 4 . g. 

 1.0 - 4.0 g. 



6.0 -30 g. 

 0.5 - 1.5 g. 



1 1. 



Avoirdupois 



44 - 88 gr. 



6 oz. 

 -232 gr. 

 -232 gr. 



350 gr.- 4 oz. 



29 - 87 gr. 



1 gal. 



Number 9 will give negatives of normal contrast on many negative eniulsions in 

 5 to 7,min. at 65°F. for tray development. For tank use, this may be diluted with an 

 equal quantity of water to obtain longer developing time, of the order of 14 min. at 

 65°F. If desired, this developer may be mixed double the indicated strength and 

 diluted appropriateh^ at the time of actual use. 



