Quote Originally Posted by DBP
I was experimenting with tea toning yesterday and today and decided to try belaching with either bleach or ammonia. Rather than mess up some good prints, I started with some badly overexposed prints that had been printed from a negative with too little density range for a Cyanotype. And I couldn't find the ammonia bottle, so I grabbed some window glass cleaner (containing ammonia and isopropyl, plus ingredients unknown) and mixed it roughly 1:3 with water. Shortly after I put the prints in, I noticed that the lighter areas were bleaching out faster than the darker, restoring the contrast to normal. I think I have recovered several prints this way now, though all have gone a bit purple. Will post some scans when they dry.
Do not mix household bleach or any hypochlorite containing product with ammonia containing products. Anything with the potential to generate chlorine mixed with ammonia generating materials will produce a very toxic gas.