Emulsion paints contain only small concentrations (5-15 %) of organic solvents as co solvents. The most important volatile constituent of such paints is water. Both the water and the solvent must first be separated from the nn-volatile part of the paint, e.g. by drying at 105 °C. More accurate separation is, however, achieved by distillation, using thin-film vaporizers or special distillation units in order to suppress solvent retention which might falsify results.
Distillation temperatures may have to be raised to 150 °C or more if high boiling solvents are present. Solvents are qualitatively determined by gas chromatography, supplemented in case of doubt by infra-red analysis. Plants which do not have the necessary analytical equipment can have tests done by material testing institutes or private analytical laboratories.