EFFECT OF REFRACTORY MILL ADDITIONS ON MOLTEN APPARENT VISCOSITIES OF STEEL GROUND-COAT ENAMELS*

A viscosimeter of the rotating-cylinder type was used to determine the effect of refractory mill additions on the molten apparent viscosity of steel ground-coat enamel. A blend of three commercial frits was used as the base enamel to study the effect on molten viscosity of various amounts of silica, feldspar; and nepheline syenite. Results indicated that silica imparted the greatest increase in molten viscosity. Additions of feldspar and nepheline syenite of 9% or less increased the molten viscosity about the Same amount. With, however, a 12% addition of refractory, feldspar was more effective for increasing molten viscosity than nepheline syenite.