Sealing Slate Tile Floors Installation Servies – TheFlooringlady

To seal, or not to seal, that is the question. If you are about to install a slate floor, you have probably heard conflicting opinions about sealing your tiles.

The conflicting advice comes from the different experiences contractors and homeowners have had with slate tiles.

Different experiences come from using different types of slate. Sealing slate isn't necessary, especially if you want to keep the natural look and beauty of the slate.

However, if the stone is porous and/or you aren't experienced at grouting, seal the stone first.

 Furthermore, sealing slate is important if you want a shiny or matte finish, and if you want to protect it from staining.

You can buy chemical sealers at retail stone and home improvement stores.

Best Sealer for Your Slate Floor!

To help maintain better air quality, you want to use a water-based polyurethane sealer.

To help give the stone its best protection, a penetrating sealer is a good precaution. 

In addition to being low in VOCs (volatile organic compounds), water-based polyurethane is non-yellowing and non-cracking, giving you years of good looking slate floor tiles.

 The BulletProof Sealer by StoneTech and 511 Impregnator Sealer by Miracle Sealants are popular choices for water-based sealers.

Slate Varieties for Your Home

Slate typically comes from Brazil, Vermont, China and India.

The Brazilian and Vermont slates tend to have a low absorption rate, while Indian and Chinese have variable absorption rates. 

The softer slates need more attention with sealants before and after installation than do the harder slate tiles. Slate is a metamorphic rock, starting as a sedimentary rock and with pressure and temperature over time became slate.

It is made of materials with characteristics like clay, and it has a structure similar to layers of sheets.

Because it has some porosity, you may want to seal it to keep it from staining and soiling.

Brazilian slate

Indian slate

Chinese Slate

A bit more about the origin of your slate will help you determine how you want to treat it. Brazilian slate is typically dense and has variegated colors while Vermont slate is typically dense, smooth and one consistent color (black, blue, green red).

In contrast, Chinese and Indian slates are typically variable in density (soft to hard) and variegated coloring, with a wide range of colors.

 If you get a soft slate, typically Chinese or Indian, pre-seal with a porous stone sealer.

​Step 1: Preparation

The preparation needed before installing your slate floor tiles is to clean the subfloor where the slate is to be installed.

Clean dust and dirt from all slate surfaces, and let them dry thoroughly before applying two coats of the penetrating tile sealer.

Step 2: Application

There are surface, or topical, sealers, but the penetrating sealer gives your stone tile better protection, and looks better longer.

Apply the sealer in a thin coat using a sprayer, roller or brush, following the grain of the slate and let it dry for at least two hours and reapply (your specific product will tell you how long between coats to let it dry).

Step 3: Grouting

After you have laid the tiles, let the mortar dry and cure before grouting the tiles.

To increase the bonding strength of your mortar and grout, mix penetrating sealant with grout instead of water.

This recipe increases bond and tensile strengths and improves the water resistance of the installation.

The increased water resistance is especially important if you are installing your slate tile floor on a concrete slab that can wick ground moisture into the room.

Step 4: Finishing

What look do you want your slate floor to have -- natural, wet, or glossy? You can get the wet-look without going to glossy by choosing the right finish.

There are finishes that will look natural after application, but many people love the wet-look for their slate floor. Black Diamond Stone Works offers such a sealer with a high gloss finish.

 If you want to enhance the color of your slate without making it look too glossy, you could go for the Stone Enhancer by Auqamix.

Step 5: Washing and Cleaning

After you grout the tiles (preferably with latex grout because it increases flex strength, reduces efflorescence, and has great bond strength), let it dry, ideally for a week, before cleaning the tiles.

You want to wash the tiles thoroughly, several times, to remove all remnants of excess grout so that it won't become a permanent part of your slate floor.

Step 6: Recoating

When the tiles are dry from the washing, you can apply two more coats of penetrating sealant.

 This step is to add further protection to the slate, but also to the grout and grout-tile interface.

Step 7: Curing

After you have applied your last coat of penetrating slate tile sealant, let cure for at least 24 hours before walking on the floor.

The longer you can let it cure before walking on it, the better protection you will have, and the longer the finish will last. 

Note that the sealer needs to be re-applied after every 3 to 5 years for interior surfaces, and every 1 to 3 years for exterior surfaces, depending on the brand.

 To have a better idea on how to reseal slate surfaces, check out this video:

Caring for Slate Floors

Compared to ceramic tiles, maintaining your slate floor requires extra care. Like any object, slate tiles will age faster if neglected.

  • For a start, you need to clean it regularly if you want it to look good after many years. Wash it with mild soap and water, and dry mop or vacuum in between washings. This will remove dust and dirt, which is the main cause of scratches on most surfaces. When mopping, move in one direction instead of back and forth. Let the dust accumulate in one spit and them collect them using a dustpan.
  • When the mop is not in use, store it properly with the head off the floor.
  • It is recommended that you mop your slate floor with a damp mop at least once a week.
  • As an added protection, place a welcome mat or rug at the door. Or better yet, have room slippers ready for your household and visitors, so they can leave their shoes at the door.

Regular Cleaning and Maintenance

Highly acidic or alkaline cleaning solutions can reduce the effectivity of your sealer. It’s best to use a cleaner that is neutral, formulated specially for stones, and if possible, matches with the brand of your sealer.

The usual solution is to mix 1 part solution to 4 parts water, but you can also mix 1 part solution to 1 part water when cleaning darker stains. Clean the surface before application.

Use a sprayer, mop, sponge or scrub when applying. Some solutions won’t require rinsing after, while others will.

If you are accustomed to waxing floors, you are in for a treat because wax isn't necessary on slate.

Wax won't hurt the slate, but will obscure it's natural beauty, turn the tiles a darker shade, and may yellow the grout; all good reasons to not wax your floor.

Step 1: Identify original coating

To find out what coating was originally applied, mix one cup of ammonia with one gallon of water.

 Apply it on the floor, scrub it then wipe off. If the coating was removed, most likely wax has been use. If the coating wasn’t removed, then there’s a chance that it is urethane or epoxy based and harder to strip off.

Step 2: Removal of wax or Water based coating

  1. Mix the product in a bucket according to manufacturer instructions.
  2. Apply the mixture in a small area where you can cover scrubbing until it dries.
  3. Let the solution stay for a few minutes and then add more so it stays wet.
  4. Scrub the floor using a buffer or you can do it manually with a scrubbing pad that has just the right hardness.
  5. Rinse the solution thoroughly with water.

Step 3: Removing Urethane or Epoxy Based Coatings

When removing urethane or epoxy-based coatings, you need a strong solvent-based stripping solution. Practice safety measures by wearing mask and goggles when applying.

Also ensure that there’s proper ventilation and that you won’t disturb the neighbors. If you don’t feel confident about handling a dangerous chemical, you can always contact a professional to do it for you.

  1. Apply the solution with a brush or roller and let it sit for a few hours.
  2. Then try stripping off the coating with a putty knife.
  3. If it comes off easily, it means that the solution has taken effect and you can already strip off the coating.
  4. After this, you would need to apply the alkaline stripper.


Slate makes a beautiful flooring. Proper preparation and care of it will keep it looking great for years to come.

If you can't decide if you should seal your new slate tiles before installing them, error on the side of caution. 

Sealing them may not be necessary, but after you have installed them it will be a headache to seal them properly. 

And you may not be able to protect them soon enough, if they are porous and absorb stains.

To seal or not to seal?

Go for it with a penetrating, water-based slate tile sealer and enjoy your natural stone floor for years.

420 thoughts on “Sealing Slate Tile Floors Installation Servies – TheFlooringlady”

  1. I high sheen finish will take care of providing a wet look on slate, brick, wood, or even concrete.
    But from personal experience, a high-sheen floor finish also shows dust much more than a low-sheen floor finish. That’s especially true if the floor is dark — like black slate.
    From my personal perspective, the beauty of slate and other stone floorings is the look of the stone. When it’s sealed with a high-sheen finish, it looks fake to me, detracting from the natural beauty of the stone.
    That said, there can be lots of reasons to have a high-sheen finish on slate floors. Be sure to clean the surface well so the sealant doesn’t lift later.
    – The Flooring Lady

  2. Hi we are in the process of installing slate tiles in an outdoor walkway. The installer bought 511 Impregnator. He said the slate needs 1 coat on the bad side that will face the ground and 3 coats on the good side. I love the way it looks when wet but I am not as attracted to it when it dries. We have only applied the 511 Impregnator on the bad side, and have not applied it on the good side yet. What should I do? Should we apply the 511 Impregnator on the good side then get a wet sealer and apply over? Or if I want the wet look should i not apply the 511 Impregnator and only apply a wet sealer? I am confused on this process. I live in Northern California and only have Home Depot to get products, does anyone know of a good product to get a semi gloss look? Thanks!!

  3. I am about to install Indian Slate Rock tiles in my kitchen. I have heard that it is better to seal it first to prevent the grout from staining the slate rock. Would you advise against using a xylene based paver/stone sealer?

  4. I personally would advise strongly against using xylene-based products. Xylene has been associated with various health problems, and I strive for healthy environments, which start with the materials you use indoors.
    Check with your flooring company to see what sealant alternatives they have for you. To avoid health problems, avoid using xylene.

  5. I’ve never heard of using oils like that to seal slate. And the use of linseed oil for sealing wood is often discouraged because it encourages mold/mildew growth on the wood. I’d think they would not be the right products to use on a slate floor, or any floor for that matter.

  6. I am also getting ready to install a slate floor on my front porch. While covered, it does get wet during a heavy Florida rain. I like the wet look to bring out the most color, but I also do not want the tile to be slippery when wet. Will the sealers make the tile more slippery?

  7. As long as you don’t apply thick layers of sealant, you should be fine. If you apply two light coats, allowing them to dry completely between applications, you should enjoy the wet look without a slippery treachery.
    The key is to not build a heavy layer on the surface, letting the natural texture of the Saltillo tile through. Make sure there is no remaining old sealer present on the surface before you apply the new product you’ll have good results too.
    Test a small area first, preferably on scrap of tile or in an out-of-the-way spot, to see end results prior to completing entire project.

  8. I have old slate floors that are in good condition but never sealed. Want to seal them with a matte finish but they also need to be cleaned first. What should I do?

  9. Just installed beautiful green slate floor-a uniform color. Sealed as explained on bottle of $40 sealant and floor dried with some blotchy spots. It looks as if baby oil or olive oil fell on those spots (it didn’t.) We let the floor dry thouroly before walking on it.
    My contractor is mystified.
    Do we strip off the sealant and start again? (Strip how??)
    Or should we apply another layer of the sealant??
    Thanks for your advice.

  10. Hi,
    We put a sealant down a few times on our slate floor and the sealant just doesn’t seem to last. It fades and the floor goes back to looking “dirty and blah”. We decided to put down some transeal (clear gloss varnish to give it a lasting shiny poly finish), however, it looks like it may be beading because of the sealant we previously put down. Do we need to remove the sealant first before applying transeal ? If so, how do you recommend removing the sealant?
    Thanks so much,

  11. Stone flooring needs to be cleaned carefully before sealing it for the first time. Carefully means using the cleaner that won’t harm the stone. For example, vinegar on a sandstone floor could cause damage. Before you use any cleaner on your stone, check it out in an inconspicuous area first.
    Regular sweeping/vacuuming and damp mopping will keep a stone floor in good shape longer than when you let the grit and grime build up.
    If you need to reseal a stone/brick/tile floor — and they do need annual resealing, if you go with the same product you used initially just reapply the product. But if you are changing sealing products, check the compatibility of the new and old sealants by testing in an inconspicuous area. You may need to strip the old sealant off before applying a new sealant. Ask your flooring manufacturer, installer, or the store where you bought your flooring product for suggestions of how to best remove the old sealant.
    If you find spots appearing on the tile after you’ve sealed it, chances are some chemical got into the stone before you sealed it, even before you bought it. Extracting it could be challenging because it may have become part of the stone makeup.

  12. I had a slate flor laid and sealed, but the tiles still look slightly white as if dusty in parts. Is this natural or do i need to unseal,clean and re-seal? Thanks

  13. The white haze is not natural. You may not need to completely remove the sealant that’s there; you may need to thin it.
    The haze could be caused by several things. It could be the use of a water-based sealant that’s not formulated for slate floors, in which case you probably do need to remove it and start again.
    It could be that too much sealant was applied, the coats after the first are pooled and giving the white haze look. In this case you could use a white buffing pad under a regular rotary machine.
    Don’t hesitate to ask the manufacturer of your slate for input either.

  14. I don’t have personal experience with Indian slate outdoors. My best guess, from what I do know about slate, is you should seal it before installing it so you don’t get it absorbing moisture and minerals from your soil.
    But do check with the manufacturer/provider to see what they say and learn about their warranty.

  15. Just wondering if you can use any floor cleaner (ie: Mr. Clean, PineSol, Swiffer, etc) for regular cleaning of slate tile floor?

  16. I’m sure the manufacturers of those products would say you can use them with no problem, but I’d think they might be too strong for the slate, especially if the slate hasn’t been sealed. For air quality reasons I’d say avoid those products too.
    But of the products you mentioned, Mr Clean would be the one I’m most suspicious of being too strong. I personally would use a vinegar water solution on the floor — a 1:10 vinegar:water solution — to clean my floors with.

    • Ummmm, you keep saying do NOT use a vinegar solution to clean slate floors, but you just suggested using vinegar! ? I know it’s a very diluted solution – 1 part vinegar to 10 parts water – but that seems contradictory. ? Also, we are renting a home with slate flooring and don’t know what was previously used, or if the floors were sealed. (I’m assuming they were.) Landlord doesn’t know either. I physically cannot be on my hands/knees to strip, clean, seal the floors. Neither can the new Mom with a 1 week old baby. Are we doomed to hiring a professional?

  17. My flooring installer is currently preparing to install a copper quartzite floor in my home. I understand quartzite is similar to slate. This stone has an irridescent metallic look to it,expecially when wet, and depth, like you’re looking into a canyon. I would like to maximize the ability to see those features after sealing. Any suggestions?

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