Dirty fireplace stones can make an otherwise clean room seem dirty and dingy. Commercial companies offer to clean fireplace hearths, but hearth cleaning can be easily done at home with a few household tools. Several commercial cleaners can remove soot from stones, but commercial cleanings can damage some older, softer stones. It's important to choose cleaners and cleaning methods carefully to avoid damage to the fireplace.
Spread the dust sheet around the fireplace to protect flooring from water spots and soot seepage. Plastic drop sheets are better for protecting surfaces such as carpeting that are easily stained.
Mix cleaning solution by adding one cup of salt to one cup of dish detergent in a small mixing bowl. Stir to make a loose paste.
Dip the nylon brush into the cleaning solution, and clean the soot off in a small, circular motion with the brush on an inconspicuous area of the fireplace to test if the stones will hold up to cleaning.
Continue scrubbing stones if the stones are resilient enough to withstand cleaning. Simply sweep the stones and dust well if stones crumble or show signs of distress.
Wipe the stones down with a damp sponge. Clean from the front of the hearth to the back of the firebox to make sure the brush and bucket remain as clean as possible. Repeat these steps as necessary to clean all stones.
Scrub crevices of stones with a nylon pad or toothbrush dipped in the soap and salt mixture.
Use a toothbrush to clean mortar lines between stones. Dip the toothbrush in the cleaning solution, and scrub with an up and down motion. Use care to not scrub too hard on the mortar, especially in places where it may be crumbling.
Wipe the stones down with a clean sponge. Rinse the sponge frequently to prevent smearing soot onto other stones. Change your water frequently.
Dry stones and mortar lines thoroughly by rubbing them down with an old towel.
This is a mild cleaner that may not work as well on tough jobs. Try using Trisodium Phosphate for tougher jobs. Trisodium Phosphate can be found in home improvement stores and should always be used with gloves. Replace the soap/salt mixture with ½ cup trisodium phosphates diluted with a gallon of hot water.