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HANDBOOK OF PHOTOGRAPHY 



formulas are used with stocks originally 

 tending to low contrast and under condi- 

 tions of low agitation. With greater agita- 

 tion the activity is often reduced by 

 reduction in concentration or alkalinity. 

 The developer activity may be still further 

 reduced when very low contrasts are desired 

 with emulsions of high-contrast type. The 

 typical example of this is the development 

 of variable-density sound tracks recorded 

 on positive motion-picture film. 



The effective life of these formulas is 

 usually rather short, as their activity drops 

 rather rapidly with use from exhaustion of 

 the reducers and accumulation of products 

 of development. 



This type of formula has also been 

 applied to the development of other kinds 

 of negatives and such developers have 

 become generally used in both commercial 

 and amateur negative developments. Sev- 

 eral typical borax negative developers are 

 given in Table II. 



Developer 1 is a low-concentration 

 borax type particularly applicable to agi- 

 tated machine development for work in 

 which low contrast is desired. 



Developer 2 is more concentrated and 

 consequently more active than 1. It may 

 be used in machines where shorter develop- 

 ing times are desired. It may also be used 

 with commercial and amateur negatives, 

 particularly when nearly stagnant develop- 

 ment is used. 



Developer 3, as listed, has about the 

 same activity as No. 2. If greater activity 

 is desired, more borax and less boric acid 

 may be used, keeping the total amount 

 constant, and correspondingly^, for less 

 activity, the boric acid should be increased 

 and the borax decreased. 



Developer 4 is the least active of the 

 group cited. It is used when lowest con- 

 trasts are desired, as in the case of variable- 

 density sound tracks from records origi- 

 nally on motion-picture positive. This for- 

 mula has the peculiar property of increasing 

 in power to give contrast, as it stands after 

 mixing and before use. 



Carbonate Developers for High Con- 

 trast. Positive. — In the development of 

 prints and variable-area soimd-track rec- 



