Boron Nitride Cera Patch is a trowelable putty for patching, repairing and filling any fissure, crack or defect in refractory materials, leaving a nonwetting layer for molten metals. Containing no refractory ceramic fiber (RCF), it is designed to expand to fill damaged areas with no sintering, shrinkage or cracking with thermal cycling. The putty is not sensitive to freezing and has a long shelf life. Boron Nitride Cera Patch is usable in all atmospheres at temperatures of 1472-1832°F (800-1000°C).