Quote Originally Posted by mdm View Post
Any yellow stain?
mdm's question is in regards to use of diazidostilbene sodium sulfonate.

The answer is yes and no. And that it seems to depend on the paper used for final support.

The sensitizer itself in solution is nearly clear, and does not seem to have an intrinsic stain, like the diazo sensitizers that have been discussed earlier in this thread.

On my first test, I used a microporous inkjet paper, which i use sometimes for quick-and-dirty tests, to avoid using up my fixed-out photo paper. It has a tendency to show stain readily (even with dichromate and cyanotype), and it did. There was a significant brown stain that appeared within 2 hours of development and drying.

The second test was on fixed-out FB paper, and it only started to show very faint stain about 12 hours after drying.

Both were cleared about 36 hours after drying, using the formula posted earlier in this thread and in the UltraStable thread. Both cleared readily, without the frilling and emulsion damage that mdm reported in his tests.

Can anyone reading this thread explain the chemistry of clearing these prints, especially the role of the potassium permanganate? For reference, the formula can be found here.