Regarding potassium dichromate, yes, chromium is a known carcinogen and were I you I might well avoind it myself. However, in the minutely small amounts that dichromate is used as a contrast agent in kallitype and Pt./Pd. printing (typical would be 1ml of a 5% solution of potassium dichromte in a liter of developer) I personally do not believe there is any health risk involved.
My articles at unblinkingeye and the alternative photography site clearly state that my kallitype method is based on 1) simplicity and 2) permanence. This is achieved by the use of one developer and toning with one of the noble metals.
BTW, I am fairly certain that you could obtain contrast control with kallitype using the Na2 method that many people are using with Pt./Pd. printing. See Dick Arentz's website for dilutions of Na2 to match Pt./Pd. printing to negatives of various contrast. Since light sensitivity is based on ferric oxalate in both kallitype and Pt./Pd. the contrast controls that work with one process should work with the other.
Originally Posted by Wayne
Last edited by sanking; 03-09-2006 at 08:09 AM. Click to view previous post history.