ISO 1265:1979

Specification of a visual method of determining the number of impurities and foreign particles in polyvinylchloride resin. About 200 g of resin are flattened between a rigid white plate and a glass sheet containing a grid. The impurities and foreign particles visible in 25 squares (= 225 cm ) and having a diameter equal or greater than 0,250 mm are counted. Expression of the result by extrapolation as the number of specks per 100 squares of the grid.