The document specifies a method for assessing the stability in hard water of surface active agents which are readily soluble at ambient temperature or slightly higher temperatures.
DIN EN 12458:1999 history
1999DIN EN 12458:1999-04 Surface active agents - Determination of stability in hard water; German version EN 12458:1999
1999DIN EN 12458:1999 Surface active agents - Determination of stability in hard water; German version EN 12458:1999