Pyro Processing Temp.

[Silverpixels5]

Can pyro be successfully used at temperatures other than the reccomended 65-70F? I want to try this developer out, but my darkroom stays a constant 75F in the summer. Any info on the subject would be greatly appreciated.

 

[ptempel]

Sure, I develop at 75F (24C) all the time. Hutchings mentions that you can go as high as 80F in his "Book of Pyro." Any highr than that and the film will swell up and even reticulate (grain becomes clumpy). I'm assuming, of course, that you mean Pyrogallol and not Pyrocatechin when you say "Pyro." I've used PMK (pyrogallol based) but have never tried any pyrocatechin type devs. The liquid PMK dev kit from Photographer's Formulary makes it really easy to mix and use.

 

[sanking]

Pyrocatechin based developers (Pyrocat-HD and Diaxactol) tan and harden the emulsion as effectively as Pyrogallol developers ( PMK. ABC Pyro, Rollo Pyor, WD2D). All can be used for high temperature development up to about 80F or slightly higher.

If you already know the correct development time for a particular film at 68F, but want to develop at 75-80F instead, a general rule is to decrease develoment time by about 3-5% for every degree over 68F. The actual percentage increase varies with film, film/developer combinations, whether pre-soak is used, etc., but 3-5% should get you in the ballpark for most conditions.

Sandy King