Potassium bromide antifoggant, 18% solution

Description

The classic inorganic antifoggant as a ready solution. It restrains development and raises contrast — a tool both against fog and for shaping the character of a print.

How it differs from benzotriazole

Bromide is blunter: it restrains development generally, not only where there is no latent image. So it raises contrast more and slows the process, but it does not shift paper tone cold the way benzotriazole does. On warm-tone papers that is often the deciding difference.

In practice

A few millilitres per litre of working developer, then adjust by result. An excess lengthens development noticeably and can clip the shadows.

Questions and answers

Which one for expired film?

Usually benzotriazole — it targets fog more precisely. Bromide when you also want more contrast.