> Been thinking about using dichromate in pot. ox. developer for pt/pl prints
> and can find no info as to replenishment as it relate to time and use. After
> searching the archives and various books....to no avail I thought that
> someone might have some experience with this. I have a feeling that as with
> h2o2 the replenishment is not a very exact science. Any thoughts?
> Thanks in advance
>
I've been using the dichromate method of contrast control for pt/pd
for a while now with no apparent loss of activity of the dichromate.
I replenish in 200ml increments when necessary. Last winter I ran a
series of tests using a 21-step wedge on Cranes Platinotype developed
in K oxalate with sodium dichromate in quantities of 0, 1, 2, 4, 8,
16, 32, and 64 drops per 200ml. Since my "darkroom" has been in
storage for the last 6 months and I have not been able to do any
printing, I think the first thing to do now that I'm set up again is
to test the effectiveness of my developer(s). Of course, this may not
be valid for developer that has been in coninuous use. I'll report
back with my results, hopefully in a week or so.
I am also forwarding a message from Mike Ware regarding the use of
dichromate in KOx and the strange and beautiful crystals that I once
found in one of my bottles.
In actual practice, I rarely find it necessary to use the dichromate.
If negatives can be made to be printed without the use of contrast
enhancers such as sodium dichromate or potassium chlorate, that to me
is the best of all possible worlds. Sometimes a small amount of
H2O2 may be added to the "emulsion" to clean up the highlights but
that's about it.
Keith
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Keith Schreiber
Rights and Reproductions
Center for Creative Photography
University of Arizona
Tucson, Arizona 85721
Fon: 520-621-7968 Fax: 520-621-9444
Email: keith@ccp.arizona.edu
WWW: http://www.ccp.arizona.edu/ccp.html
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