Relation of Surface Structure of Glass to HF Acid Attack and Stress State

The surfaces of commercial glasses (mainly borosilicate glasses) were investigated by HF etching and surface‐stress measurement. The HF etch rate was slow at the surface for some phase‐separated glasses, which was attributed to excess alumina in the surface layer produced during the glass manufacture. After heat treatment of the glass rods, either with or without the as‐Received surfaces, compressive (tangential) stresses were observed in all the glasses studied. These stresses were probably caused by evaporation of water from the surface during heat treatment. Copyright © 1979, Wiley Blackwell. All rights reserved