The Composition and Properties of the Chief Types of Commercial Glasses

JSGT 1937 V21 T415-T427

Formerly glass manufacturers were compelled to employ glass compositions of high lime and. low alkali contents, because of the expensiveness of soda ash and sodium sulphate. Wherever possible natural raw materials were utilised. With the introduction of automatic machinery in bottle and sheet glass manufacture these compositions were no longer suitable on account of their high melting temperature and great tendency to devitrification, and it was necessary to employ more alkali and less lime in the composition. This decreased the durability of the glass, which, however, was still sufficient for containers in general. The Mylius classification of chemical resistance, together with durability results obtained by the powder method, permitted the durability's of soda–lime–silica glasses to be predicted. The conclusions agreed well with the durability results obtained by other workers for containers of different alkali contents.

G. Keppeler