PMK and Rollo Pyrogreenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
Would someone please take a moment to describe the difference in Rollo Pyro and PMK. Also, my B solution PMK has begun to develop a gritty solution on the bottom. I filter this out but don't get the stain I used to. Can anyone explain this.
-- kevin kemner (firstname.lastname@example.org), August 22, 1999
Sometimes if solutions get to cool they will do that. What is Rollo Pyro? Never heard of it. Pat
-- pat j. krentz (email@example.com), August 23, 1999.
Can't help you on the grit, but Rollo Pyro is a variation of PMK. If I remember correctly, Dick Sullivan claims that PMK oxidises too fast in JOBO drums. This reduces the developer's abiity to produce stain. So he came up with this formula. It is basically PMK with additional Sodium Borate. Keep in mind, it is only meant to be used in drums. For trays, stick to normal PMK.
-- Robert Lyman (firstname.lastname@example.org), August 26, 1999.
In my previous post, I said that Rollo Pyro contains added "borate". I was wrong. Apparently it contains additional potassium bromide and vitamin C. The purpose, as I said before, is to slow down oxidation in rotary processers. Sorry about the mix up. I hope it hasn't caused problems for anyone.
-- Robert Lyman (email@example.com), August 27, 1999.