Despite the clear advantages of borates in glassmaking, they have never been used in the manufacture of heavy clay products. New developments, however, are now making it possible to use borates in such products, allowing manufacturers to improve fired ware quality while also saving energy. The main barrier to the use of borates in heavy clay products has been the form in which it is used rather than its function. A new form of borate ( Evansite ), a microfine sodium pentaborate in a sugar suspension, has been developed specifically to meet the needs of the heavy clay industry. The sugar prevents the borate from migrating to the surface of the clay body during drying. The borate can then dissolve in the body, ensuring optimum distribution and even vitrification. Once the body is dried, the sugar is burned off during firing, and the borate can begin fluxing. Test results have confirmed this. Other benefits include reduced water absorption, enhanced freeze-thaw durability, and enhanced raw material capabilities. Environmental benefits are also mentioned.
Primary author(s): Austerberry M; Stubbs A