Developing agents amidol

For very low temperature processing a caustic solution of two powerful developing agents, such as amidol and pyrocatechin, may be required, as used in Kodak SD-22. 

Method 1. The classic developing agent for creating cold tones on bromide papers is amidol. However, PQ developers using organic antifoggant, such as benzotriazole, will also increase the amount of cold image tone in a print (Formulas Paper Developers, Blue-Black Developer). In either case the results are usually very subtle. 

The best papers to use with amidol developer are old-style, soft emulsion papers, such as those with minimal hardener, silver-rich papers (papers without excessive dye sensitization), graded bromide papers, long-scale chloride papers, or specially coated papers such as David Lewis Bromoil Paper (see Resources). With any other paper, which is to say most modern chlorobromide papers, amidol works just as well, though not necessarily better than most other developing agents, or combination of developing agents—thus the controversy. 

Notes Amidol is one of the finest developing agents for blue-black tones on soft-emulsion bromide paper. It is also capable of creating neutral-blacks with a fine scale and transparency in the shadows. 

Uses As a preservative of developing agents constituent of the acid fixing bath blackener in negative intensification active energizer in amidol development. 

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