This document specifies a titrimetric method for determining the esterified-acid content in binders for paints and varnishes@ free acids and acid anhydrides being necessarily included in the result obtained. Because different binders vary in their resistance to saponification@ this document is of limited applicability. If necessary@ completeness of saponification can be checked by repeating the test under more severe conditions achieved by the use of longer saponification time@ more concentrated potassium hydroxide solution@ or a higher-boiling alcohol as solvent. Annex A specifies a procedure suitable for binders that saponify with difficulty. The method is not applicable to those materials that show further reaction with alkalis beyond normal saponification.