A.W. Perkins Furnace Cement is a premixed silicate cement that withstands temperatures over 2000 degrees F without failure. It adheres to firebrick, as well as metal, and seals all types of stovepipe joints. It's black, non-gritty formula feathers very thin to make metal-to-metal joints smoke and gas tight. Use during installation and service of furnaces, stokers, oil burners, and small woodstove repairs. Apply 1/16" - 1/4" thick.