How to Seal Slate Flooring Tiles

How to Seal Slate Perfectly in 3 Easy Steps

Slate is a common material chosen for floors and countertops. Slate naturally comes sealed and looking polished, but with time, the tile sealant can wear down and needs to be touched up to get it back to looking brand new. Luckily, it’s about as easy as buying the right products and having a fair amount of patience.

Important Notes about Slate

Slate is a highly porous natural stone material and has natural grooves and pockets that dirt and debris love to hide in. When not properly polished or sealed, Slate flooring will quickly absorb an liquids spilled and this leads to staining.  When Slate is properly sealed, the barrier not only helps seal the natural stone from liquids but it provides a thin buffer that protects it from scratches and everyday wear and tear.  Do a quick water drop test to see if your flooring is in need of sealing, just drop a small amount of water:  Did it bead or get absorbed in the tile?  If it was absorbed it’s time to seal your slate. Here are the 3 options you have when sealing your slate:
  1. Polish or Wax—These last about 6 months in high traffic areas and around a year in low traffic areas.  A thin topical coat ensures that liquids and dirt don’t penetrate your tile.  It’s important to note that every 6-12 months this product will need to be stripped and then reapplied.
  2. Penetrating or Impregnating Sealers—Just as the name implies, penetrate into the cracks and crevices as well as surface pores and seal the tile.  Any dirt or liquid will have a hard time finding a new home in your tile which makes clean up a breeze.  Some penetrating sealers advertise the ability to keep your slate sealed for more than 10 years.  
  3. Topical Sealers—This is the middle of the road, not as serious or chemically strong as a penetrating sealer but stronger than a wax.  There’s a balance between all the work required in preparation and how easy the product is to work with.  Topical Sealers have an average wear lifespan in the 3-5 year range.  Another advantage as Topical sealers will change the look of your slate, and if you’re looking for a nice glossy finish this is your best option.

Step 1: Buying the Right Slate Sealer

When selecting a tile sealant, try to buy one that’s made specifically for stone surfaces. There are spray-on sealers and sealers which you can apply with a brush. Spray-on sealers make for easy application, but brush-on sealers are relatively cheaper, even though they take more time to apply. If the grout, the white parts in between the tiles, isn’t sealed, or you feel like it could stand for re-sealing, there are 2-in-1 sealers especially made for sealing slate (or stone in general) and grout at the same time.

Step 2: Clean Before Sealing

Sweep and mop the floor with a combination of water and dish detergent. After letting the floor dry, you can go over it again with a mixture of bleach and water – refer to the instructions on the back of the bleach bottle to get the ratio right – and over the surface once more with a natural stone cleaner. Make sure to rinse after each mopping and cleaning. Use an acetone stripper to remove extra grime if needed. Make sure to rinse the surface after doing so.

Step 3: Sealing Slate

Assuming you’re using a brush-on sealant, apply one thin coat of sealer to the surface with a paintbrush – for spray-on sealants, perform as instructed by the manufacturer. Wait for two hours and apply a second coat. If you feel applying additional coats is needed, do so after two hours of applying the previous coat. After applying the final layer, wait 24 hours before walking on the floor.


WikiHow recommends a small amount of linseed oil before sealing to give your slate a glossy finish.