Print developers bromide solution

There are a number of differences between Phenidone/Hydroquinone (PQ) and Metol/ Hydroquinone (MQ) print developers, but none of them are significant enough to cause one to be preferred to the other. Perhaps the most important difference is the longer and more consistent working life of a PQ developer. This is because Phenidone is less sensitive to bromide so the build-up of bromide in solution has little effect on its activity. However, it should be noted that the organic restrainers found in high pH PQ developers are carried off by the print. While this will not affect the activity of the developer it will have some affect on the overall contrast of succeeding prints. 

To increase the flexibility of MQ and PQ print-developing formulas, keep a bottle of carbonate solution and a bottle of 10% bromide on your darkroom shelf. I learned this trick from photographer Edna Bullock, who learned it from her husband, Wynn Bullock. Wynn used this technique with Ethol LPD paper developer. 

Many toning processes in photography involve the use of selenium compounds.6 One such process recently recommended consists in treating the print or lantern slide, after developing, fixing and washing, with a solution containing about 1 per cent, of crystalline sodium sulphide and 1 per cent, of sodium selenite or selenious acid after twenty minutes or so in such a bath intense brown tones are obtained with chlorobromide papers, or brown-violet tones with pure bromide papers.7... 

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