From: Sandy King (sanking@clemson.edu)
Date: 01/02/02-10:36:09 AM Z
Hi folks,
Let me try to clear up a misunderstanding about the Pyrocat-HD formula.
1) The Pyrocat-HD formula as published at The Unblinkingeye Eye is
correct. The formula is .
Stock Solution A
Distilled Water 75ml
Sodium bisulfite 1.0g
Pyrocatechin 5.0g
Phenidone 0.2g
Potassium bromide 0.2g
Water to make 100ml
Stock Solution B
Distilled Water 100ml
Potassium carbonate 100g
Working solutions are mixed 1 part A + 1 part B + 100 parts water for
a developer with working characteristics similar to PMK. At 1:2:100
or 2:2:100 the working solution performs much like ABC+ (Rollo Pyro).
The only difference between the Pyrocat formula found at the
Unblinkingeye and the original formula published in Post-Factory
Photography is that the original formula used a stock solution B of
10% sodium carbonate (with a basic working dilution of 1 part A + 10
parts B + 100 parts water). The change to potassium carbonate was
made primarily with consideration to mixing and storage requirements
since there is little if any difference in the working
characteristics of this developer regardless of which of the two
carbonates is used.
2) The present misunderstanding results from a Note to the article in
The Unblinkingeye , which states, "The formula provided here differs
from the one published in Post-Factory Photograhy, issue #4.
......... An earlier version of the formula published on the
rec.photo.darkroom newsgroup called for .25 grams of metol in place
of the phenidone. Mr. King suggests that this formulation may be more
stable than the phenidone version."
In fact, the earlier version that was published on the
rec.photo.darkroom newsgroups called for 2.5g of metol per 100ml, not
0.25g. From information provided by Linas Kudzma it now appears that
the lower amount of metol may be sufficient for the formula to work
as intended. However, all of my early testing with the Pyrocat-HD
formula, which I called PCMC at the time, was done with metol in the
amount of 2.5g per 100ml of stock solution A.
Hope this information clears up some of the present confusion.
Sandy King
>Several people have written me saying .02 grams of phenidone couldn't
>possibly be right, and they are correct. I had the correct formula on my
>site all along. It does indeed contain .2 grams of phenidone, as was
>correctly published in Post-Factory Photography. I humbly apologize for the
>confusion.
>Ed Buffaloe
>http://unblinkingeye.com
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