This standard specifies a method for the determination of light absorption of cellulose acetate, employing test specimens taken from two mouldings which have been produced using different periods of heating. The aim is to provide quantitative measurements which are compatible with visual judgements of yellowness and lightness, and of changes in these properties after moulding. The determinations are carried out on cellulose acetate in plasticized form rather than in solution, since a more reliable guide is thereby obtained to the performance of cellulose acetate in plastics materials.