The Hardness of Glass

JSGT 1950 V34 T077-T079

The resistance of glass to grinding and the resistance to indentation do not provide the same measure of hardness. Since resistance to grinding is of widespread importance in the glass industry, the author has attempted to measure it in terms of the volume of glass per minute removed by grinding by a specific abrasive applied under a fixed pressure. From the “grinding hardness” (GH) values so obtained for glasses of differing composition, factors have been calculated for the effect of each 1% of the oxide present. The highest values are those of the glass-forming oxides silica and boric oxide.

W. H. Willott