Sandy King (sanking@hubcap.clemson.edu)
Sat, 23 Jan 1999 00:20:15 -0400
Hi Liam,
Thanks very much for your recent post re: bleach/redevelop of Agfa step
wedges. You might be interested to know that I recently conducted a very
controlled experiment which involved the following.
1) Processing of 4 enlarged step wedges via your reversal process as
published in Post Factory Photography.
2) Bleach of the four wedges in a super-proportional reducing agent
(potassium dichromate + hydrochloric acid + potassium bromide) and
redevelopment in PMK for 5, 10, 15 and 20 minutes.
The results, showing original density (read through B&W channel) and
resulting density after development in PMK (read through Blue channel),
are as follows.
Redevelopment Time Original Density Redevelopment
5 minutes .13-1.71 .08-1.39
10 minutes .13-1.77 .10-1.60
15 minutes .13-1.75 .10-1.70
20 minutes .13-1.71 .12-1.74
You will note some slight differences in the original density of the step
wedges. Perhaps this can be explained by time in the clearing bath, as you
suggested in a private message. I was not aware that this might be a
variable until you made the suggestion (after I ran the above tests).
I can report that I have made some really nice carbon prints from negatives
made by the "Lawless" reversal process (on Arista APH) which were
subsequently bleached and redeveloped in Pyro. The major purpose of the
bleach/redevelopment was to reduce contrast of the original reversal
negatives (shall I admit incomplete control of your process), and to this
extent the procedure worked admirably. A side result was the stain, which
may or may not be a plus.
My intention is to continue the experiment and compare printing qualities
in carbon of original and redeveloped negatives to ascertain the exact role
of the stain. I am very interested to see the results of further
experimentation of bleach/PMK redevelpment for contrast control because the
original work suggests the potential of a very powerful tool.
Meanwhile, thanks for sharing the results of your experiments with us, and
welcome to the alt-photo-process list.
Sandy King
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