Rich;

You are talking about 2 things, stabilization and toning. These are different.

For sulfur toning follow the instructions on sulfur toning and for use of Sistan follow those instructions. The concentration and formulation of the sulfur compounds are very different, and the results are quite different.

After fixation, no soluable silver should remain. The formation of oxidized silver compounds is one of the reactions leading to image degradation.

PE