Cleaning and Sealer Suggestions For Slate Floors

June 23, 2012 Off By Torin Dixon

Question: – I have approximately 1000 sq ft of interior slate flooring and approx 1300 sq ft of new Vermont green (the closest we could find to match the interior) exterior slate flooring.

The  interior slate was installed around 1988 and was sealed on installation.  It has had no treatment, other than cleaning, since then.

What do I need  to use (and how much) to clean and seal both interior and exterior slate?


John B.


Hi John,

Thank you for contacting us with your questions. I may need more information to fully answer your questions but I will give you some basic ideas.

Regarding the existing slate, you did not mention the condition. Is it clean without any stains? Does it have any noticeable coatings or sealers? Is it glossy or dull looking? Does it get darker when you mop or clean it? Do you like the existing look?

The answers to these questions will affect the recommendation of products. For instance, generally we suggest you deep clean slate and all stone prior to sealing with the R55 Intensive Cleaner:

Once clean, rinsed and dry we suggest the following products depending on your preferences:

For a “Green” alternative sealer that is water based we suggest the S32 Water Base Sealer:

For a clear natural look (the way the slate looks when clean and dry) the best product is HMK S34 Silicone Impregnator. This is an invisible sealer that protects agains stains and make regular cleaning easier. This is also a penetrating sealer that goes down into the pores of the stone rather than the following topical sealers.

If you like a slight color enhancement and a soft matte finish, we suggest HMK S35 Matte Finish Sealer:

If you like more of a sheen to the slate then we suggest HMK S37 Satin Finish Sealer:

Both the S35 and S37 are Acrylic Based sealers and lay on the top surface more than a penetrating sealer. They offer a more refined & finished look than raw or natural looking stone, but will require more maintenance.

If you like the look of the stone when it is completely wet, you may want a Color Enhancing Sealer like S42 Exterior Color Enhancer, or S44 Color Enhancer for Interior floors: (S42) (S44)

Finally, once you make your selection and finish your project, we highly recommend using HMK P24 Liquid Stone Soap for general maintenance.

This highly concentrated soap is specially formulated to support the sealers to protect the sealers from being broken down by harsh cleaners. It is pH neutral, non toxic and biodegradable.

Best regards,

Torin Dixon

Natural Stone Specialist
StoneCareOnline – Stone Care Products
P.O. Box 395

Missoula, MT 59806