How to Clean a Stone Fireplace Hearth

A stone fireplace hearth can take up a small or larger area of your living room. The hearth is prone to soot accumulation and the dirt may penetrate the grout, resulting in an unappealing appearance. A stone fireplace hearth should be cleaned more frequently than brick fireplace hearths. The types of cleaners you use will depend on how dirty the hearth is and the type of grime you need to remove. In some cases, washing the fireplace hearth with detergent will suffice, while if the hearth is badly soiled you will need to use a more powerful solution such as trisodium phosphate.

Step 1 – Remove Dust

Brush the soot and dirt from the fireplace first so particles won’t fall on the hearth. Use a vacuum cleaner to simplify your task, and make sure you remove dust from the grout and other hard-to-reach places.

Step 2 – Protect Your Floor

Protect the space around the hearth with old newspapers or a dropcloth.  

Step 3 – Prepare Cleaning Solution

Clean the stone fireplace hearth with a solution of table salt and detergent. Dissolve 1 cup of detergent and 3 tbsp. of table salt into 3 quarts of warm water in a bucket.

Step 4 – Apply Cleaner

Apply the cleaner on the fireplace hearth with a sponge. Wear rubber gloves to protect your hands. Leave the solution to set in for 10 minutes.

Step 5 – Scrub the Hearth

Use a plastic wire scrub to remove the cleaning solution. Scrub thoroughly on the grout, which typically accumulates more dirt. Use a toothbrush you no longer use to clean hard-to-reach spots or the hearth.

Step 6 – Rinse the Hearth

Rinse the hearth with a soft sponge dipped in clear water. Check if any detergent is left behind and rinse several times, if needed. Make sure the cleaner will not leave traces when the hearth dries. Allow the hearth to dry before using the fireplace.

Step 7 – Remove Persistent Stains

If, after the fireplace hearth dries, there are stains remaining, use a more powerful cleaner. Choose household ammonia, which contains 5 to 10% ammonia and is an effective all purpose cleaner. Mix 1 cup ammonia with 1 lb. of finely ground pumice and water to a thick paste. Apply the paste on the fireplace hearth and allow it to set in for 10 minutes, then scrub and rinse. Ammonia is caustic, so protect your skin and eyes. If this solution does not work, try removing stains with harsher chemicals, such as trisodium phosphate, or TSP. TSP is an alkaline solution that can remove grease, oils and persistent stains. Use 1/2 cup TSP in 3 quarts of water. Apply the solution, then follow steps 5 and 6. TSP is toxic, so pay attention to not inhale it or get it in your eyes while you scrub. Wear protective goggles.