ISO 1389-3:1977

Phthalic anhydride for industrial use — Methods of test — Part 3: Measurement of colour stability

The principle is based on the measurement of the colour of a test portion, by the method specified in ISO 2211, after a specified heat treatment. The test sample is maintained in a colorimetric tube in an electrically heated aluminium block, controlled at (250 3) °C for 90 min, in the molten state. The results are expressed in Hazen units. – ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.