ISO 3620:1994 Preview
Photography -- Processing chemicals -- Specifications for aluminium potassium sulfate
This standard was last reviewed and confirmed* in 2016.
*Therefore this version remains current
Establishes criteria for the purity of photographic-grade aluminium potassium sulfate dodecahydrate, AlK(SO4)2·12H2O, and specifies the tests to be used to determine the purity.