This document specifies a test method for the determination of non-volatile matter of coatings directly after application or after intermediate or final drying. In practice, the determination of volatile matter is applied particularly in regard to water-thinnable coatings which are re-coated with an additional coating material. Furthermore, the method can be used to compare the efficiency of different application and drying methods. The content of non-volatile or volatile matter of a product after application is no absolute variable but depends on the application and drying conditions applied during the test. Consequently, applying this method gives only relative values and not the real values for the content of non-volatile matter, due to solvent retention, thermal decomposition and evaporation of low-molecular contents