How To Clean & Seal An Interior Slate Floor - Floorseal

How to clean & seal an interior slate floor

If you wish to clean & seal an interior slate floor please read on, Floorseal has all the cleaning and sealing products you require.

The products discussed in this guide are the items we think are the most useful, but the list is not exhaustive! There are other products which may be appropriate, please contact us if you cannot find what you are looking for.

Ultimately the sealer you select will depend on the location of the slate and the finish you require.

There are various types of slate fitted to interior floors, walls or used to create fireplace surrounds. The most used type of slate located within kitchens are colourful Chinese or Indian slates. Followed by more traditional grey/blue slates, which are also used on roofs or fireplace surrounds. Brazilian black slate is also quite common in kitchens, living areas and bathrooms.

Slate is a porous sedimentary material but it also quite dense. Slate often appears more attractive when damp/wet or when you use a sealer to deepen its colour. For this reason, many sealers will deepen the colour of slate or create a sheen. Some sealers will just waterproof the slate and do not alter its colour.

Most slate looks quite dull with a washed-out appearance when unsealed. There are various ways of sealing slate, but low sheen topical sealers are commonly used. Cleaning slate is quite straightforward, stripping slate of some of older sealers is not!

This article will provide guidance on how to successfully clean and seal a slate floor.

How to deep clean a slate floor

Cleaning new or unsealed slate floors, or slate floors which have been sealed with an impregnator, is quite easy. Please use Floorseal Stone Floor Cleaner for deep cleaning slate floors. This cleaner will remove ingrained dirt, oils, and other residues. It can also remove certain water-based acrylic coatings.

Stone Floor Cleaner will (with adequate dwell time) remove water-based paints and old coatings. This product is safe to use when deep cleaning dirty slate floors and associated slate surfaces. This might be wall tiles, fireplace tiles or slate furniture i.e. benches.

Stone Floor Cleaner is to be applied with a mop or brush then left to dwell on the surface, preferably for approximately 15 minutes. Do not allow the cleaning solution to dry out during this time. Add more product and/or water to ensure the slate stays wet.

The dilution rates vary and should be adapted to suit the level of soiling. This product is typically applied at a dilution rate of 1:5 with clean water (one part product & five parts water).

Rinse away with plenty of clean water, preferably neutralising the cleaning agent with a mildly acidic solution. Floorseal Cement & Grout Haze Remover can be used for this purpose. 

How to remove grout haze or cement staining

If you wish to remove cement or grout hazes, please use Floorseal Cement & Grout Haze Remover. This product can also be applied undiluted or slightly diluted. Please adjust to suit the level of soiling.

Slate is typically not acid sensitive so you can use acidic based products to remove cement-based staining. This may be from the adhesive used to fix the slate or from grouting the slate. Always test first, some black Brazilian slates can be acid sensitive.

Please rinse away with plenty of clean water.

How do I strip old topical sealers from slate floors?

Stripping old sealers is involved work and is beyond the scope of this article. For general guidance many old sealers are solvent based acrylics and require a solvent to remove them. It is a slow process and will mean working with products which have strong odours.

You will usually have to repeat the stripping process numerous times to completely remove the sealer. Indian & Chinese slate floors which were laid 10 – 20 years ago were often sealed with solvent based acrylics. These are normally shiny coatings which can still be seen around the edges of the room or on the surface of the tiles when clean.

Water-based acrylics are less difficult to remove but the process is still not easy. Floorseal Stone Floor Cleaner can remove water-based certain acrylics, but it is an involved process.

Breaking down old impregnators is usually quite straight forward and only involves deep cleaning the floor. Trying to break down a newly applied impregnator or colour enhancer is much harder to do.

If you need advice on stripping old sealers, please contact us directly.

How to seal an interior slate floor

Floorseal Slate Sealer will make this process easy. Sealing slate is beneficial as it protects the stone, enhances colour, and creates a subtle satin sheen.

Many darker natural stones, like slate, appear more attractive when sealed with a sealer which deepens colour. This usually achieved by applying a sealer which also produces a slight sheen.

Floorseal Slate Sealer deepens colour and creates a subtle sheen. This slate sealing solution will protect the slate from staining & enrich its appearance. 

Sealing a slate floor with Floorseal Slate Sealer

Ensure your slate floor is totally dry after any cleaning has been carried out. We would advise waiting for at least 48 hours or more before any sealing work is undertaken.

Please wait approximately 2 weeks for total drying and settlement of the stone before sealing the slate (when newly laid/fixed).

Floorseal Slate Sealer can be applied via flat microfibre mop but preferably by hand using a microfibre cloth. You should apply a minimum of two thin coats which are applied approximately one hour apart. You can build further thin coats, to increase sheen, if required.

It is also possible to apply Floorseal Slate Sealer with a paint pad or masonry style roller. If you use a roller or paint pad it is important to apply the product in thin coats. You should not see (or leave) any pooling or puddling.

The sealer is quite a white coloured liquid which becomes clear once applied in thin coats. This is because the sealer is partially absorbed by the slate and because the sealer contains levelling agents. The 1st coat will require more product than the 2nd as it is being absorbed into the slate.

Floorseal Slate Sealer will dry quickly, a 2nd coat is possible to apply approximately one hour after the 1st coat. Keep the 2nd coat thin and even, remember that this coat is now bonding to the 1st so you will use less product.

Applying thick coats on slate floors or walls is not advisable. Do not assume thick coats are ‘better’ they are not. Thick coats are weaker due to a slow drying and curing time. Thick gloopy coatings are usually due to a poor application technique.

Application instructions are there for a reason and supported by Technical Data Sheets (TDS). Taking your time and applying the product carefully will produce great results.

Sealing Slate in bathrooms or wet rooms

When sealing slate in bathrooms you should use breathable impregnating sealers like Floorseal Premium Impregnating Sealer.

This sealer is a stain resistant sealer, it is not visible after sealing. It is suitable for use in wet areas like shower cubicles, walls, or floors. This sealer will leave the slate with a natural unaltered/invisible seal. Premium Impregnating Sealer does not create a sheen/shine or enhance colour. 

The potential issue when sealing wet areas revolves around trapped moisture and slip resistance. Sealing with impregnators in wet areas can resolve any potential problems.

Please contact us for advice when sealing slate in wet areas.

Sealing Slate Black Brazilian Slate or sealing for maximum colour depth

If you require maximum depth of colour depth such as when sealing black slate we recommend sealing with Floorseal Flagstone Sealer.This product is a solvent-based version of our normal slate sealer. During application it will have a little more of an odour, although it is low in VOCs. Flagstone Sealer is likely to produce a darker tone/colour to the slate, the sealer also produces a low silk sheen. The method of application is the same as our water-based slate sealer. The difference being the final appearance – The slate is likely to be a darker shade. Usually you will only require x2 thin coats. The drying time may be a little longer at around 2 hours depending on the temperature of the room and airflow. 

In conclusion

Floorseal Slate Sealer should be applied to dry unsealed slate in thin coats with up to hour of drying time between coats. It is water-based and does not contain VOCs so is low odour. This product creates a sheen and is suitable for kitchen/living area walls and floors. It will deepen colour and create an attractive satin finish. Samples are available on the product page under the select size option. 

Floorseal Flagstone Sealer is a solvent-based version our normal water-based Slate Sealer. It is more likely to deepen colour and suited to Black Brazilian slate and plain single coloured grey/blue slate. Particularly if the slate appears too pale with a washed out pastel appearance. This product also has a low silk sheen. Samples are available under the select size options on the product page.

Floorseal Stone Floor Cleaner is a non-acidic deep cleaning solution which will remove ingrained dirt, grime, and oils. It can remove certain old water-based acrylic sealers (it will not remove solvent-based acrylic sealers). This deep cleaning solution is diluted with water and is low odour. 

Floorseal Cement & Grout Haze Remover is for the removal of cement and grout hazes. Typically, from cement-based adhesives or grouts. This product can also remove fresh efflorescence & general mortar staining. The solution can be used in a highly diluted form to neutralise Floorseal Stone Floor Cleaner. This product is low odour.

Floorseal Premium Impregnating Sealer is an invisible breathable matt finish impregnating sealer. Suitable for use in wet areas or anywhere you do not wish to alter the appearance of the slate. This product does not create sheen or shine.

Further information

Please Click Here to view our products & accessories for cleaning and sealing slate floors. This includes all of our handy ‘how to’ guides for cleaning and sealing interior and exterior slate floors.

The information included in this article is not exhaustive. If you need further information please contact Floorseal or email [email protected]