Kevin O'Brien (kob@paradise.net.nz)
Wed, 07 Apr 1999 08:42:34 +1200
I have not worked wth pyro negs yet but some of this may be useful.
For conventional silver containing negs and transparencies, bleach and
re-development adds density and modifies contrast and can, generally, be
repeated; there are various combinations with increasing density that will
work all the way up to line material. They were used routinely by earlier
workers. The classic, hydochloric acid-dichromate/MQ (Dektol), as used in
reversal processing, is a good starting point. The metalic ones give higher
densities and some are super proportional.
Sepia (sulphide) toning works well too as a final step adding another
significant actinic boost. It can follow other intensification. I like the
easy, odour free & inexpensive thiourea formulation. It's also possible to
bleach/re-develop and re-sulphide.
Formulas available directly on request.
Kevin O'Brien
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