RE: Iron Processes with Dichromate - calibrating curves

Michael, If I were to try and create such a curve, I'd start with fresh
developer for each sample type i.e. Volume of developer with X amount of
dichromate. While keeping the % solution of dichromate constant, vary it's
concentration in several batches of developer. Go to an extreme of contrast
range within your developer so that the strongest one goes a touch beyond
your normal end point. I don't think you really need to concern yourself
with how it works, if you are measuring what it does, just that it does it
so much at a given concentration in the mix. Measure your results and
repeat those results with fresh chemistry. Go back and also use your
seasoned developers and compare results. Or just go about printing and
see if after measuring you can plot points and make good extrapolations
based on your data points.

But most important is have fun and be safe.

EJ

Eric Neilsen Photography

4101 Commerce Street

Suite 9

Dallas, TX 75226

http://e.neilsen.home.att.net

http://ericneilsenphotography.com

-----Original Message-----
From: Mike Klemmer [mailto:mklemmer@comcast.net]
Sent: Saturday, January 08, 2005 11:11 AM
To: alt-photo-process-l@usask.ca
Subject: Iron Processes with Dichromate - calibrating curves

I have a few questions for the experts out there pertaining to the use of K
dichromate in iron process developers, i.e. Kallitype process. How exactly
does the dichromate act to increase contrast on the print? Is Dichromate
itself consumed (reduced) during the process of development by oxidizing out
the iron? I'm curious about this because I'd like to try calibrating a
negative correction curve with K Dichromate in the developer and am not sure
how to proceed.

Shall I assume that K Dichromate is being consumed in the process at roughly
the same rate that as the replenishment with fresh developer? So therefore
I should begin with developer that has no dichromate, but with a starting
replenish charge of developer contining the K Dichromate?

Michael Klemmer
Received on Sat Jan 8 13:55:27 2005