This fireplace mortar is formulated especially to patch fireplace fireboxes and to bond firebrick to firebrick. Fireplace mortar is a silicate product that when fire cured, sets rock hard – as strong as firebrick itself and withstands 2 000 degrees fahrenheit. Comes in a convenient cartridge for easy re-pointing of fireplace brick within the firebox. Not for exterior use. Colors match most mortars. Passes ASTM E136 and E72. 10.3 oz. cartridges.
Fireplace Mortar must be heat cured, or a white powder forms on the surface and adhesion loss may occur. Air dry Fireplace Mortar for at least 24 hours but no longer than 30 days before heat curing. Heat cures the mortar, making it water insoluble. If repairing cracks larger than 1/8″, we recommend layering. Air dry between layers. When final layer is track free then heat for final cure.