1.1 The purpose of this standard is to establis the conditions for testing the fastness of dyes to alkalis 1.2 The composition of the clay is very variable, depending on the place or origin of the clay, therefore the verification of the resis ance of the dyes to this agent, based on a single formula, lends itself to false interpretations. Consequently, two formulas are indicated below for its determination. In order to obtain maximum security, these methods are quite vigorous.