How to Paint Limestone Fireplace Mantels

Slip on a pair of rubber gloves, safety goggles and a respirator. Create a mixture of three-quarters cup tri-sodium phosphate, one tablespoon liquid dish soap and one-half gallon lukewarm water in a plastic bucket.

Stir the ingredients until they are well-incorporated and dampen a plastic scrub brush with the mixture. Work the TSP solution into the limestone mantel to remove the soot, efflorescence, dirt and debris.

Dampen a separate rag with plain water and use it to thoroughly wipe down the limestone to remove the TSP residue. Allow the limestone mantel to dry for at least eight hours, or overnight.

Cover the limestone mantel with a thin coating of latex masonry primer. Use a natural-bristled brush or small roller to apply the primer. Allow the primer to cure for at least two to three hours before continuing.

Apply a thin layer of latex masonry paint to the limestone mantel. Using a natural bristled brush or small roller, cover the mantel with the first thin layer of the paint. Allow the paint to dry for at least one hour.

Apply a second and third thin layer of the masonry paint, allowing the coats to dry for at least one hour in-between. Allow the final coat to dry for at least eight hours, or overnight, before using the mantel or fireplace.