Heat Stop II is a dry-mix, non-water soluble refractory mortar used in the installation or repair of high-temperature resistant firebrick and masonry in bread or pizza ovens, boilers, fireplaces, flues, furnaces, incinerators, kilns, and wood stoves. Is non- water soluble and may be used in exterior applications. Resists temperatures to 2,500 degrees. Meets all state and national building codes. Meets A.S.T.M. C-199. You will need approximately 50 lbs. of product to lay up 100 firebrick. Shipped in a 10 lb. jar. Remember, shipping is FREE when you place an order of $100 or more (continental US only). Consider adding some of our masonry color or tools to your order.