Corrosion of the inner walls of glass tank furnaces is a well-known source of defects in glass. Refractory materials that are typically used in glass tank furnaces are zirconia, alumina and silica-based bricks. Other oxides of magnesium or calcium might be applied as well. The materials should have high mechanical strength, excellent thermal shock stability and good corrosion resistance to liquid glass and gaseous reaction products. Temperature and chemical corrosion and mechanical erosion issues can however occur in time, resulting in an increase in the number of glass faults or defects.