Hercules® High Heat Furnace Cement is a ready to use, air-setting, high temperature refractory and retort cement for mortar facing, caulking or coating. Adheres to most building materials and when cured makes a positive non-porous, fireproof, acid proof seal that will not crack or crumble. Behold the power of Hercules®, products built to last and trusted by plumbers to withstand even the toughest conditions.