How to Clean a Stone Fireplace Hearth

A wood-burning fireplace with a stone hearth.
What You'll Need
Duster brush
Vacuum cleaner or broom
Old newspapers or dropcloth
Table salt
Bucket of water
Rubber gloves
Plastic wire scrub
Old toothbrush
Finely ground pumice
Protective goggles
Long-sleeved shirt
Trisodium phosphate (TSP)
Face mask

A stone fireplace hearth can take up a lot of area in your living room, and the hearth is prone to soot accumulation and dirt penetrating the grout, resulting in an unappealing appearance. A stone hearth needs to 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(TSP).

Step 1 – Prepare the Area

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

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

Step 2 – Prepare Cleaning Solution

You will want to clean your stone fireplace hearth with a solution of table salt and detergent. Dissolve one cup of detergent and three tablespoons of table salt into three quarts of warm water in a bucket.

Step 3 – Apply, Scrub, and Rinse

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

After it has set, use a plastic wire scrub to remove the cleaning solution. Scrub thoroughly on the grout, which typically accumulates the most dirt. Use an old toothbrush for cleaning those hard-to-reach spots.

Rinse the hearth with a soft sponge dipped in clear water when you're done scrubbing out all of that dirt. Rinse several times if needed, checking between rinses for any detergent left behind. This will make sure the cleaner will not leave traces when the hearth dries. Allow the hearth ample time to dry before using the fireplace again.

Step 4 – Remove Persistent Stains

If, after the fireplace hearth dries, there are still stains remaining, it's time for a more powerful cleaner. First, try household ammonia, which contains five to 10% ammonia and is an effective all-purpose cleaner. Mix one cup ammonia with one pound of finely ground pumice and water to create a thick paste. Apply the paste on the fireplace hearth, allow it to set in for 10 minutes, and then scrub and rinse. Ammonia is caustic, so protect your skin and eyes with long sleeves and protective goggles.

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 a half cup of TSP in three quarts of water for your cleaning solution. Apply the solution, then follow through step three. TSP is toxic, so again, wear proper safety gear like gloves, goggles, and a face mask. Also pay attention to avoid inhaling fumes or getting it in your eyes while you scrub.