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Pyrogallol - 1:2:3-trihydroxybenzene
C6H3(OH)3
Molecular Weight : 126
Characteristics : Fine white powdery crystal.
Pyro has had quite a renaissance in the last 8 years since Gordon Hutchings introduced the PMK formula which has been successfully marketed in kit form by several companies. Pyro is a staining developer and the yellow staining is proportional to the amount of silver reduced. Therefore the highlights will stain the most and the shadows the least.
Also this staining works very well to mask the grain of the negative. PMK is NOT a fine grained formula and yet reasonable quality enlargements can be made from the miniature negs from 35mm cameras. In fact I highly recommend this developer for 35mm usage for just this reason.
The only caveats with pyro are it's toxicity and it's limited stability. Make no mistake, people have died from pyro poisoning. Honestly they fell into a vat of it that was used as a clothing dye . Nevertheless, all good precautions should be taken when mixing and I usually mix mine outdoors on a calm day.
In addressing the issue of stability we should remember that pyro formulas have little sulfite and therefore are far less stable than their preserved non-staining counterparts. The developer should be mixed immediately prior to use and used only in the one-shot method.
BTW, while pyro is very unstable in alkaline solutions, it is very stable in acidic solutions and can be stored for years in a full bottle.
Pyrogallol - 1:2:3-trihydroxybenzene
C6H3(OH)3
Molecular Weight : 126
Characteristics : Fine white powdery crystal.
Pyro has had quite a renaissance in the last 8 years since Gordon Hutchings introduced the PMK formula which has been successfully marketed in kit form by several companies. Pyro is a staining developer and the yellow staining is proportional to the amount of silver reduced. Therefore the highlights will stain the most and the shadows the least.
Also this staining works very well to mask the grain of the negative. PMK is NOT a fine grained formula and yet reasonable quality enlargements can be made from the miniature negs from 35mm cameras. In fact I highly recommend this developer for 35mm usage for just this reason.
The only caveats with pyro are it's toxicity and it's limited stability. Make no mistake, people have died from pyro poisoning. Honestly they fell into a vat of it that was used as a clothing dye . Nevertheless, all good precautions should be taken when mixing and I usually mix mine outdoors on a calm day.
In addressing the issue of stability we should remember that pyro formulas have little sulfite and therefore are far less stable than their preserved non-staining counterparts. The developer should be mixed immediately prior to use and used only in the one-shot method.
BTW, while pyro is very unstable in alkaline solutions, it is very stable in acidic solutions and can be stored for years in a full bottle.
