Re: Iron Processes with Dichromate - calibrating curves

I do not know the exact mechaism of how it acts, but I can give you some
general guidelines that have worked well for me with both kallitype and
palladium prnting using both sodium citrate and potassium oxalate
developers. But not for VDB!!

First, make up a stock solution of 5% potassium dichromate, i.e. 5 grams
of potassium dichromate in 100 ml of water. Add this to the developer in
the following amount according to the DR of your negative.

DR 1.80 1 ml of dichromate
DR 1.65 2 ml of dichromate
DR 1.50 4 ml of dichromate
DR 1.35

> 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 Sun Jan 9 10:34:49 2005