ISO 3251-2019 "Determination of non-volatile-matter content in Paints, varnishes and plastics" specifies methods for the determination of non-volatile matter content in paints, varnishes, plastics and related products. This standard applies to various polymer dispersions, condensed Resins and latex, such as phenolic resin solutions. Solvent volatilization, thermal analysis and evaporation of low molecular weight components are taken into account in the determination process, so the results obtained are relative values rather than absolute values. The standard cancels and replaces the previous version, updates the references to terms and definitions, and adjusts the test methods to reflect technological advances and the use of New materials. ISO 3251-2019, developed by ISO/TC 35/SC 9, is an important reference standard used worldwide to assess the non-volatile matter content of coatings and plastics.