Non-asbestos. Spreads easily, bonds and seals metal-to-metal and metal to masonry joints under 1/8”. Durable as firebrick when heat cured. Resists temperatures up to 1093°C (2000°F). Use when installing or resetting furnaces or oil burners. Prevents air and gas leaks in flue and chimney joints. Can be used on cast iron, steel or firebrick.