With fall weather upon us, there’s nothing cozier than gathering around a stone fireplace. The sounds of the crackling wood and radiant warmth emanating through the stone can soothe your cold weather blues—but before you go lighting a match, you may want to give the stones around the fireplace a good cleaning. Not only will it extend the life of the hearth, but it will also bring out the charm of the stone.
Step 1 – Prepare the Area
Take out any wood from inside the fireplace and sweep away remaining ashes with a fireplace brush so that debris won’t get onto the area you're cleaning. Then, thoroughly vacuum any loose grit or dust. Once the debris is fully swept away, make sure the area surrounding the hearth has drop cloths or newspaper to protect your floors. Painter’s tape and plastic are good for protecting any adjoining walls from run-off and spray. Put old rags or t-shirts at the bottom of the hearth to soak up any excess water and drips.
Step 2 – Protect Yourself
Even if you're using mild cleaners, wearing rubber gloves is a must. You will likely need to do some scrubbing, and your hands will thank you for using proper gloves. Protective eyewear such as goggles is also highly recommended because even dirty water can cause irritation. Long-sleeve shirts and pants are also a good idea and if you are using chemicals, a disposable breathing mask is essential. Open windows if you can to air out any solution vapors.
Step 3 – Choose a Cleaning Solution
The types of cleaners you use will depend on how dirty the hearth is and whether it’s been sealed properly in the first place. Start with the mildest cleaning options first and working your way toward any corrosive solutions. If the area has been sealed, washing with warm water and a cloth may suffice. If that doesn’t do the trick, mix one cup of detergent and three tablespoons of table salt into three quarts of warm water to take off tougher grime. (The salt adds extra scrubbing power.)
Apply with a sponge or consider using a spray bottle and leave the solution to set in for 10 minutes. Use a wire or nylon brush to scrub the stone and grout lines, which accumulate the most dirt. An old toothbrush is useful for cleaning hard-to-reach spots.
For a slightly stronger cleaner, mix two tablespoons of borax with one tablespoon of detergent into four cups of hot water and put this into a spray bottle. For larger quantities, multiply the amounts and mix in a bucket. Use a sponge or a paint brush to apply. Again, let the solution set for 10 minutes.
Regardless of what cleaning solution you used, rinse the hearth with a sponge dipped in clean, warm water, making sure that no detergent or cleaning residue is left behind. This will ensure that no streaks or traces will be noticeable when the hearth dries. Use extra rags and t-shirts to pat dry the stone, allowing ample time for drying before using the fireplace again. (A dehumidifier can speed things up!)
Step 4 – Remove Persistent Stains
If the hearth has been severely neglected and the stains are more severe, you may need to use harsher chemicals to remove the soot. Start by mixing a paste of one cup ammonia with one pound of ground pumice (this is a natural abrasive/ exfoliant that can be found at bath and beauty supply stores) and just enough water so that you can apply the mixture directly to the tough spots. Once again, allow it to set in for 10 minutes, and then scrub and rinse.
For really stubborn stains, you may need to use 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, and follow the same steps for rinsing. The main thing to remember is that ammonia is caustic and TSP is toxic, so take the proper steps to cover up and protect yourself. It's better to apply more elbow grease with the milder cleaners in order to avoid using ammonia or TSP.
Step 5 – Seal Your Stone Hearth
After you’ve got the stone sparkling again, consider sealing the hearth. A sealant applied to a stone fireplace will prevent soot and other stains from marring the finish, and will allow you to clean with hot water and a cloth instead of extensive labor and chemicals the next time around. Talk to your local fireplace or natural stone retailer about what kind of sealant will best protect your type of stone hearth.