This document specifies two methods for testing the resistance of raw optical glasses to attack by aqueous acidic solutions and defines a classification of optical glasses according to the acid resistance determined by these methods.

The surface method tests the resistance of the polished plate-shaped optical glass to attack by aqueous acidic solutions at 25 °C for a specified time and indicates the class determined by this method as “SR-S”.

The powder method tests the resistance of crushed granular optical glass to attack by an acidic aqueous solution at above 98 °C for 1 h, and indicates the class determined by this method as “SR-P”.