From: Sandy King (sanking@clemson.edu)
Date: 01/02/02-11:11:29 PM Z
Judy,
About the Pyrocat formula.
>
>I'd like to include the latest upgraded info in Issue #7 for those who
>want it in print and/or aren't on the list, BUT---
The only change to the Pyrocat-HD formula since its publication in
Post-Factory was the use of a 100% potassium carbonate solution
instead of the 10% sodium carbonate solution, with the resulting
change in working dilution. This formula is now on The Unblinkingeye
and is same as what I sent to the list today. If you like, include
this formula, with the note that the 0.2g of phenidone can be
replaced with 2.5g of metol with a slight loss of effective film
speed.
>
>I'm confused about the metol. If the version on the rec.darkroom
>newsgroup was before Post-Factory (albeit with another name), and had the
>metol, whichever amount, why wasn't it in the P-F version? Or did you
>change your mind again? Or ...???
At the time of publication of PF #4 I was in the process of
continuing experimentation to improve the formula. I considered, and
still consider, that the phenidone version published in Post-Factory,
and now on the Unblinkingeye with substitution of potassium carbonate
for sodium carbonate, to be the best version of the formula. The
metol version was something that I had been experimenting with
earlier, and posted to the rec.photo.darkroom list, at least a year
before issue #4 was published. So, the metol version is not an
improvement, just an earlier version of the formula. However, some
persons apparently picked up Ed's note on his site about the earlier
version of the formula using metol, and since most people have metol
on hand and not phenidone it appears that quite a number of folks
have made the substitution and it has worked well for them. This does
not surprise me because the only significant difference I saw in my
tests between the phenidoe and metol in the formula was a slight
increase in speed with the former.
I hope this messages clarifies rather than confuses?
When can we expect Issue #7 of PF?
Best,
Sandy
>
>I gather it worked with just the phenidone, since at the time reports were
>good. So do please unconfuse...
>
>best,
>
>Judy
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