Sandy King (sanking@hubcap.clemson.edu)
Sat, 20 Feb 1999 19:07:52 -0400
A few quick remarks to previous points re: Rollo Pyro.
Regarding the stability of Stock Solution A of Rollo Pyro, I did not mean
to imply that Rollo Pyro does not have good keeping qualities, only that it
does not appear to be as stable as PMK. Since PMK is very possibly the most
stable complex developing mixture ever formulated we perhaps should not be
surprised that Rollo Pyro's stability is more modest. In any event, I base
my suggestion that Rollo Pyro is not as stable as PMK on the following.
1) I mixed some PMK in 1995 which I used on occasion to develop film. Its
characteristics did not change significantly from 1995 through the summer
1998. In July of 1998 I added 10g of ascorbic acid to about 750ml of
remaining Stock Solution A. This solution is now still useful but it is
decidedly less active than before I added the ascorbic acid.
2) To support this observation, Haist notes that developing solutions
containing ascorbic acid are subject to oxidation.
I can see that Rollo Pyro would work very well with Ziatype printing, as
Carl Weese remarks, taking advantage of the system's self-masking features.
For the same reason I would think Rollo Pyro would also be an excellent
developer for negatives to be used for albumen, POP and salted paper
printing.
By the way, I am currently working on an article on Pyro
developers.Information about actual working dilutions and developing times
with different films in Rollo Pyro such as that given by Carl Weese would
be appreciated.
Sandy King
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