Crack and Joint Sealant is a unique, breathable, silicone elastomer, used to seal small holes and visible cracks in chimneys. Think of it as a paintable caulk. Use it for sealing minor cracks (up to 1/8) and defects in mortar joints where the mortar and chimney are otherwise sound. This allows you to easily correct these defects without the time and expense of tuck-pointing. Dries in about 6 hours to a cloudy (milky white) film that will not significantly change the chimneys appearance. Available in a one pint container. Remember, shipping is FREE (continental US only).