Use 25ml per 1 liter of diluted fixer or stop BathNot for use with powder fixer.
Tetenal Hardener Liquid 1L.
Tetenal Fixer Hardener liquid is a hardener additive for all liquid fixers and stop Baths. A hardener additive will harden the surface of the photographic material that is being fixed. Best to use with materials with soft emulsions.