From: Sandy King (sanking@hubcap.clemson.edu)
Date: 02/28/01-06:23:48 AM Z
Michael,
The Pyrocat formula delivers the same high resolution qualities as PMK and
ABC+, together with the same qualities of separation in the highlights, and
it has has several advantages over PMK. It is less toxic, gives a slightly
higher effective film speed (much higher than ABC+), and causes less uneven
staining. Plus, pyrocatechin is much less expensive than pyrogallol.
Pyrocat also has good stability in stock solution, tested to at least 6
months, though in this regard PMK, which is stable for years in stock
solution, is better.
With the 1:1:100 dilution, development times are virtually identical to
those of PMK. For the more energetic 2:2:100 dilution, which I use for all
of my 7X17 and 12X20 negatives that are to be printed in carbon, I can
provide you on request information from my film tests for development to a
specific CI with a number of films, including HP5+, BPF, FP4+ and TRI-X.
Sandy
>Sandy,
>
>This is very good information. I am unfamiliar with the pyrocat
>developer, and
>am wondering if it exhibits the same type of sharpness, acutance, and high end
>separation that the 'traditional' pyro developers do.
>
>Ultimately, I was thinking that I would like to try pyro for the dual use
>characteristics, which you have already said is similar to PMK, but also
>because
>of the performance claims that this most vaunted developer has garnered
>from the
>likes of Mr. Hutchings, and many others.
>
>If it is similar, then this may be the way to go in the Jobo.
>
>Thanks for the input,
>
>---Michael
>
>Sandy King wrote:
>
>> Nzé Christian wrote:
>>
>> >Hi all,
>> >
>> >Sure pyrocatechol give a stainign but the color of this stain is more black
>> >than yellow green. And Carl, you will loose the "possibility" to print your
>> >neg in platinum or on classic bromide paper.
>> >Pyrocatechol also got the same tanning effect as his cousins pyrogallol.
>> >
>> >regards
>> >Amicalement
>> >
>> >Nzé Christian
>>
>> That is not my experience. The stain I get with the Pyrocat formula is not
>> black at all but very similar to what I get with PMK and ABC+. It is
>> *slightly* less intense and the color is more greenish brown than the
>> yellow green you get with PMK and ABC+ but it acts just as effectively as
>> an actinic filter for UV light with alt processes and with VC papers. In
>> fact, I find it is slightly *more* effective as an actinic filter for UV,
>> which of course makes sense since brown is more effective than green at
>> blocking UV light.
>>
>> Sandy King
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