Chrome alum hardening fixing bath recommended for hot weather processing. Also known as Ansco 202.

IngredientQuantity
Solution A
Sodium thiosulphate320
grams
Sodium sulfite anhydrous
20grams
Water to make
1
liter
Solution B
Chromium potassium sulphate60grams
Sulphuric acid8mililiters
Water to make1liter
Pour 1 part Solution B into 3 parts Solution A, whilst stirring A rapidly.

This formula, when freshly mixed, is especially recommended for use during hot weather, but it rapidly loses its hardening properties, with or without use. Useful life is only 1 day.

Scum which may form on the surface of the negative when an old bath is used is removable by swabbing with cotton-wool before the negative is dried.