Cleaning Slate Floors

Kitchen with slate flooring

David Papazian/Getty Image

Slate flooring may literally be as hard as a rock, but it does require regular maintenance to look its best. There are several common cleaners and cleaning tools you can use on slate—as well as some you should never use. When it comes to stains, a household agent usually does the trick. And while regular cleaning is important for looks and to prevent undue wear on the flooring, sealing the slate (and grout lines) is the best way to protect this porous stone from stains and everyday dirt. 

Basic Slate Floor Cleaning

The most important thing you can do regularly to maintain a slate floor is to keep it free of loose dirt and debris. These small particles can act like grits of sandpaper, wearing down the protective sealer and making tiny scratches in the tiles every time the floor is walked on. You can clean slate floors regularly with a broom, vacuum, and/or a mop.

  • Broom: If you opt to sweep your slate floors, choose one with soft bristles that will not scratch the surface, doing more harm than good.
  • Vacuum: Vacuuming isn’t always the most effective method for cleaning dirt from a slate floor, but it can be useful if done on a regular basis. Just make sure that you have a soft nose attachment that will not scratch the slate surface.
  • Mops: Dry Swiffer-style products can be particularly effective at getting rid of hazy dust and dirt that may accumulate on your slate floor. You can also clean slate floors with a wet mop, but always wring out the mop after rinsing. Don't allow large puddles of water to form, and don't leave water on the surface. Use plain water, or add a few drops of mild dish soap for occasional deep-cleaning. 

What Not to Use on Slate Floors

Never use acidic or abrasive cleaning products when mopping a slate floor or when spot-cleaning stains. Acidic cleaners, including ordinary vinegar, cause a chemical reaction that can etch the stone. Strong cleaning agents can strip the sealer on slate and grout. Also, never use oil-based cleaners or dust-mop treatments. Oils can make the floors slippery and can clog up the crevices and textured surface of the stone. 

Removing Stains From Slate Floors

Ordinary rubbing (isopropyl) alcohol can be used as a natural disinfectant for slate flooring and is a good stain remover. Mix 1/2 cup of alcohol with 1 quart of water and clean with a sponge or mop. In the case of stubborn stains, scrub with a towel or cloth.

Another natural stain remover is hydrogen peroxide. Mix a few drops into a quart of water and then apply it with a mop or sponge. This is particularly good for getting stains out of the surface of individual pieces.

There are a number of fragrant essential oils which can be mixed in with other cleansing solutions to give them a refreshing scent. They do not have much stain removal or disinfection power, but they are able to fill an environment with a light airy feel. Just avoid using more than a drop or two per quart of water mix.

Sealing Slate Floors

Natural, unsealed slate is porous and will soak up water and liquid staining agents. These can cause dimensional discolorations in the material and can degrade the mortar bed, underlayment, and subfloor below. The best way to prevent all of this is to seal the slate and grout on a regular basis, usually every three to five years.

There are two types of sealant that should be used on a slate floor. A below-surface, or penetrating, sealer will seep down into the material, clogging the pores so that unwanted agents cannot get in. Then a barrier sealer can be applied to create a clear protective coating over the surface to provide extra protection.