Reaffirmed 2019

NATIONAL FOREWORD

This Indian Standard which is identical with IS0 9689 : 1990 ‘Raw optical glass-Resistance to attack by aqueous alkaline phosphattiontaining detergent solutions at 50%-Testing and classification’, issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Optical and Mathematical Instruments Sectional Committee (LM 20) and approval of the Light Mechanical Engineering Division Council.

In this adopted standard certain terminology and conventions are, however, not identical to those used in Indian Standards, Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appearreferring to this standard, they should be read as ‘Indian Standard’.

b) Comma has been used as a decimal marker while in Indian Standards the current practice is to use full stop (.) as the decimal marker.