本方法适用于不含添加剂、填料等的醋酸纤维素，这些添加剂、填料等可能会干扰粘度的测定。它适用于乙酸产率超过50%的醋酸纤维素。用邻苯二甲酸二甲酯增塑的醋酸纤维素在规定的温度、压力和时间条件下成型。冷却后，模塑件被磨碎。根据ISO 1157测定模塑研磨材料的粘度比以及原醋酸纤维素材料的粘度比。粘度损失百分比由成型前后的粘度值计算得出。第二版取消并取代第一版ISO 1599:1975。

This method is suitable for cellulose acetate which does not contain additives, fillers, etc. which may interfere with the determination of viscosity. It is suitable for cellulose acetate having an acetic acid yield above 50 %. Cellulose acetate plasticized with dimethyl phthalate is moulded under specified conditions of temperature, pressure and time. After cooling, the moulding is ground up. The viscosity ratio of the ground material from the moulding and also that of the original cellulose acetate material are determined in accordance with ISO 1157. The percentage viscosity loss is calculated from the values of viscosity before and after moulding. This second edition cancels and replaces the first edition ISO 1599:1975.