What do I use to Clean and Seal my Slate Tiles?


Hello and thank you for your help. We have slate from India that we installed in our Longboat Key Florida home two years ago. It is our only flooring inside the home and outside on our terrace. We are directly on the gulf of mexico and the slate floor on our terrace gets salt air exposure and spray from the ocean and a good amount of sun light. We love the look of the slate and the feel and texture of the floor. Inside it is holding up well but the outside terrace has dulled, looks chalky in spots and is breaking up and flaking more than inside. Our contractor did put a sealant on after installation. The product was SIGMA Penetrating and topical sealer from Sparks Manufacturing.

My question is what is the best or recommended way to care for the slate? We want to clean it professionally outside and seal it. I am totally confused as to what product to use for this as I have read many opposing recommendations. I have looked into water based sealers, petroleum based, epoxy based solvents , and others but as mentioned am confused and I don't want to ruin the floor by using the wrong product. Can you make a recommendation?


ANSWER - Slate will wear from the exposure to the weather.  If it is spalling (flaking) it could be due to the stone be subjected to excessive moisture.  The white chalky spots could be efflorescence, which is also a symptom of a moisture problem.

If the moisture that gets under the stone by going through the grout joints and it has no way to drain away that is a condition that subjects the stone to excessive moisture.

On the other hand, it is normal for a natural stone to need re-sealing at least once a year.  You can use an enhancer sealer that is breathable and will give the tile a wet look and bring out the colors, and help minimize moisture getting through the grout joints.  The stone has to be thoroughly cleaned and dry before sealing.  You can go to our website under the Resource Directory for Cleaners and Sealers at https://ctasc.com/category/resources/cleaners-sealers/ to obtain links to some manufactures of these products.

There are also professional stone restoration companies who can do this work for you.  Just make sure they are experienced and qualified to do the work.

2 thoughts on “What do I use to Clean and Seal my Slate Tiles?

    • Donato Pompo says:

      Slate roof tiles can be sealed, but it is only temporary and it doesn’t make them waterproof. The roof waterproofing is under the slate and if the slate is installed correctly in a weather orientation then that together with the roofing membrane keeps it waterproof.

      There are many natural store waterproof sealers. some are Enhancers that give the stone a wet look. Although you will have to continue to reapply every 6 months to a year to maintain the look and the performance.

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