Black Furnace Cement is a pre-mixed silicate cement that withstands temperatures over 2000 degrees fahrenheit without failure. The smooth consistency feathers very thin to make metal-to-metal joints smoke and gas tight. For installation and service of furnaces and oil burners. Seals flues and coal or ash pit doors. Also for small wood stove repairs. Item 64C is packed in cut case. Special order: 50 Gal. Drums.