How to Clean a Stone Fireplace

A few winters of fires can leave your fireplace in need of a good cleaning. Smoke and soot can waft out and leave the stone dingy. You don’t need a pro to put the sparkle back in your hearth. Here’s how to clean a stone fireplace. 

Lay a plastic tarp on the floor to protect it from the cleaner, and duct tape the edges to hold it down and prevent leaks. You can buy a commercially prepare enzymatic cleaner, or you can make your own by mixing trisodium phosphate (a heavy-duty cleaner available at hardware and home improvement stores) into a bucket of warm water. Check the package for the correct ratios. The dirtier the fireplace, the stronger you need to make the solution. Add 2 to 3 ounces of bleach per gallon to your TSP solution. Scoop all the fire and ash debris from inside the fireplace.  

Pull on a pair of gloves and goggles to protect your hands and eyes. Make sure you have proper ventilation by cracking a window. TSP is a strong cleaner that needs to be handled carefully. Keep a pile of towels handy to catch runs and spills as you clean. If your fireplace is very dirty, apply the cleaning solution with a sponge and let it sit for a few minutes. Next, pick up a stiff-bristled brush (metal-bristled brushes are best) and start scrubbing. Stone is porous and holds on to dirt. You’ll need to scrub hard to clean all the nooks and crannies. Scrub the stone and the mortar. If streaking occurs while you’re cleaning, dilute the TSP solution with more water. 

An important part of knowing how to clean fireplace stone is removing tough stains that are resistant to scrubbing. Make a paste of water and TSP and put it on the stained area. Let it sit for a few minutes. Scrub hard. You’re going to use a lot of elbow grease on this project.

Finish by sponging water over the stone to rinse off the cleaning solution. Let the stone air dry before removing the plastic tarp. After cleaning the mantle, apply a stone sealer that will make it more stain-resistant. Now that you know how to clean stone fireplace, you’re going to want to do it as infrequently as possible. It’s hard work.

Note: You may want to test some of the cleaning solution on a small spot to make sure it won’t bleach or streak the stone. Apply the solution and let it air dry.