From: Sandy King (sanking@clemson.edu)
Date: 07/17/03-02:14:56 PM Z
The pyrocatechin (catechol) sold by Artcraft works fine. The stuff is
quite different from the look we expect for pyrocatechin but I have
tested and know that it gives the same results as the white granular
variety that we are more familiar with.
Regarding the substitutions, I don't highly recommend them. The
substitution of meter for phenidone will result in a slight loss of
effective film speed, and the substitution of sodium hydroxide for
potassium carbonate may give negatives that show more grain. I know
people who are making both substitutions and are very happy with them
but based on my research and tests the formula with phenidone and
potassium carbonate give the best results.
About the small amount of phenidone, bear in mind that there is
fairly wide latitude in the amount we can use in the formula and
within certain limits we get the same results, and the limits are a
low of about 0.1g to a high of about 0.4g. The exact amount of
potassium bromide is a bit more critical.
In any event the stock solutions have very good keeping qualities, up
to around 6 months without any change of development qualities, so I
mix the solutions in quantities of 1000ml each. This makes the
measurements much less critical.
Pyrocat works fine with a wide range of development routines, in
tray, tanks and rotary. I recommend using a slow rate of rotation
with Jobo since fast rotation can cause a lot of oxidation that can
give increased fog stain, not desirable. This would be most
noticeable with fast films like HP5+ that are developed for a very
long time. I usually add a pinch of sodium sulfite directly to the
working developer just before use when developing films like HP5+ and
Bergger BPF for N+ conditions.
Regarding time of development and effective film speed, this will
vary a lot depending on the desired negative density range, which
logically would match the exposure scale of the process being used.
Here are some suggestions for Ilford FP4+, and the PhotoWarehouse 125
ASA films same. The recommendations are based on rotary processing in
tubes or drum at about 72 degrees F, with a relatively slow
(10-15rpm) rate of rotation. Increase times by about 15=20% for tray
development.
Carbon and Platinum printing, for a density range of 1.4 with normal
SBR, use the 1:1:100 dilution and develop for 14-15 minutes. Or use
the 2:2:100 dilution and develop for 8 minutes.
Kallitype and Palladium, for a density range of 1.75 with normal SBR,
use the 2:2:100 dilution and develop for 13 minutes.
Albumen, Salted Paper and Vandyke, for a density range orf 2.00, use
the 2:2:100 dilution and develop for 20 minutes. Be sure to add a
pinch of sodium sulfite to counter developer oxidation.
Also, have a look at Clay Harmon's data on Pyrocat-HD at
http://unblinkingeye.com.
Just remember that Clay's development information is for Palladium
printing and would give excessive contrast with silver printing,
including AZO.
Hope this helps.
Sandy King
>Today I got some Catechol to make some Pyrocat for the first time,
>and I had a couple of questions...
>
>What should Catechol look like? I got a pound from Artcraft
>Chemicals & it is a shade darker brown than say Starbucks' Mocha
>Frapuccino : ) which seems consistent with what I have heard, but
>what i have not heard, is what to look for in the consistency of the
>granularity. Mine is a mixture of small, flat chips between a
>quarter & an eigth of an inch in diameter. There are also granules
>the size of brown sugar mixed throughout. I haven't tried to break
>the chips up and didn't know if this was a bad sign.
>
>Another question I have is whether or not it matters that I only
>have a scale that measures in half grams. Sandy's formula (a la
>unblinking eye) calls for .2g of potassium bromide; if I measure a
>half gram and separate 2/5 by eye, is that negligible? I am going to
>use metol instead of phenidone for Sol A, and the 10% sodium
>hydroxide in Sol B. Does this all sound peachy?
>
>The only other thing I am curious about is a general sense of what
>other users are using for developing times/routines & ISO ratings
>for HP5 & FP4+. I shoot both 120 & 4x5 in these films. I hand
>develop with a spiral tank for 120 & use a Jobo Expert 3010 by hand
>for 4x5. Are there special considerations when developing this way?
>
>Thanks!
>
>-Joe
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