This International Standard specifies a method for determining the non-volatile-matter content by mass of
paints, varnishes, binders for paints and varnishes, polymer dispersions and condensation resins such as
phenolic resins (resols, novolak solutions, etc.).
The method is also applicable to formulated dispersions containing fillers, pigments and other auxiliaries (e.g.
thickeners and film-forming agents). For the method to be usable for unplasticized polymer dispersions and
rubber latices, the non-volatile residue (which consists essentially of the polymeric material and of small
quantities of auxiliaries such as emulsifiers, protective colloids, stabilizers, solvents added as film-forming
agents and — especially for rubber latex concentrate — preserving agents) has to be chemically stable under
the test conditions. For plasticized samples, the residue, by definition, normally includes the plasticizer.
NOTE 1 The non-volatile-matter content of a product is not an absolute quantity but depends upon the temperature
and period of heating used for the determination. Consequently, when using this method, only relative and not true values
for non-volatile-matter content are obtained owing to solvent retention, thermal decomposition and evaporation of low
molecular mass constituents. The method is therefore primarily intended for testing different batches of the same type of
product.
NOTE 2 This method is suitable for synthetic rubber latices provided heating for a specific period of time is considered
appropriate (ISO 124 specifies heating until the loss in mass of a 2 g test portion following successive periods of heating is
less than 0,5 mg).
NOTE 3 In-house methods for determining non-volatile matter often include drying with infrared or microwave radiation.
Standardization of such methods is not possible, since they are not generally applicable. Some polymer compositions tend
to decompose during such treatment and therefore give incorrect results.
ISO 3233 and ISO 23811 specify methods for determining the volume of non-volatile matter in paints,
varnishes and related products.
BS EN ISO 3251:2008 history
2019BS EN ISO 3251:2019 Paints, varnishes and plastics. Determination of non-volatile-matter content
2008BS EN ISO 3251:2008 Paints, varnishes and plastics. Determination of non- volatile-matter content
2003BS EN ISO 3251:2003 Paints, varnishes and plastics - Determination of non-volatile-matter content
1998BS EN ISO 8618:1998 Plastics - Liquid phenolic resins - Conventional determination of non-volatile matter