A report on Bleach, Silver and Ammonia

In Reversal processing, residual silver in the emulsion after the first development is reduced to a soluble silver salt using a chemical bleach, most commonly EDTA.

These compounds are used in photography to bleach silver images, converting them to silver bromide that can either be fixed with thiosulfate or redeveloped to intensify the original image.

The resulting adduct can be decomposed with ammonia to release the free alkene.

Mixing bleach with ammonia similarly produces toxic chloramine gas, which can burn the lungs.

Mixing with chlorine-containing products or strong oxidants, such as household bleach, can generate chloramines.

Experts also warn that prolonged contact of ammonia solutions with silver, mercury or iodide salts can also lead to explosive products: such mixtures are often formed in qualitative inorganic analysis, and that it needs to be lightly acidified but not concentrated (<6% w/v) before disposal once the test is completed.