Studies of Clay Mixtures for Glass Melting Pots. Part I. Resistance to Thermal Shock. Part II. Shrinkage at High Temperatures

JSGT 1931 V15 T059-T083

There is no doubt that present-day melting practice is tending to become more severe. At factories in this country melting lead glass it was, and with some still is, the custom to melt in small pots during the week-end at a temperature seldom exceeding 1350°C, and the glass thus made would last the workman from four to five days. Thus, for every 24 hours at maximum temperature the melting pot had but to withstand 1080–1150°C (the working-out temperature) for the subsequent four or five days. Contrasted with this is the system now adopted by one English factory of founding the glass overnight at a temperature of about 1450°C and working out the glass during the day, so that a founding of glass is obtained every day as against one, or at most two per week, by the former method. The above facts should be borne in mind when statements are made that the life of pots used to be months, whereas it is now measured in weeks. There are instances to be found in this country where even huge pots with a capacity of 35 cwt of molten glass have a founding cycle of 30 hours and spend their useful life in a furnace the temperature of which is maintained at 1320°C.

J. H. Partridge & G. F. Adams