Common Issues to Avoid When Caring for Your Slate

An image of a slate surface.

Slate has been a staple building material for hundreds of years, from historical buildings in Pennsylvania sporting slate features, to now where it's seeing a bit of a resurgence. With modern rustic design becoming huge over the last decade that seems to have risen hand-in-hand with the craft brewery boom. For a local example to us here, Stone Brewery makes beautiful use of it for their bar tops and flooring along with unfinished wood accents. Even with its rougher texture and look than most finished stone and a reputation for being very durable in comparison to something like marble, there are a few things to watch out for to avoid damaging a slate surface or ruining its appearance.

Here are a few common pitfalls to watch out for when caring for your slate.


Allowing Spills to Sit

Like all natural stone, slate is a porous material and can allow water and other liquids to seep beneath the surface. This can lead to difficult-to-remove stains and growth of mildew and bacteria if you're not on top of it. For that reason, it's important to always wipe up spills immediately, as even water can leave temporary dark spots and water marks in the stone if allowed to sit on unsealed stone. It's also important for this reason to use a cutting board on slate countertops, and be sure to soak up spills and juices from your meal prep that made their way onto the surface of the stone right away. Cooking grease can also leave a stain if left standing, and food/drinks that are acidic that can lead to chemical etching on the surface (more on that below). Common acids to avoid include vinegar, tomato sauce, citrus, tea and wine.

Using Acidic Cleaning Products

Acidic cleaning solutions and vinegar should never be used on slate or any other natural stone, as they will dull the professional finish and eat away at the surface of the stone and lead to etching. Etching can often look like watermarks or a surface stain, but in reality, these are chemical burns that have damaged the surface. Sealing your stone is your first line of defense here, but acidic chemicals will strip away and damage your protective sealer as well, opening you up to stains and etching in the future.

This is why it's so important to use cleaning products that are specially formulated for use on slate and other natural stone. Granite Gold Daily Cleaner® is an effective stone-cleaning solution that is pH balanced and completely food-safe. Stains can be harder to see on slate, but they really are something you can't unsee once you notice them. You do have a few ways of remedying the situation, however:

For oil or grease stains:

In order to lift oil that has seeped beneath the surface, you can create a mix of baking soda and acetone to the consistency of pancake batter to cover the affected area. Give this mixture 24 hours to work, before wiping away and rinsing with water. Some stains may require two or three attempts to fully remove. Be sure to reseal once this is completed.

For organic stains:

For stains like wine, coffee, fruit juice or tea, mix one-part laundry bleach with one-part water and spray it onto the surface (the mixed solution won’t harm stone). Scrub with a safe-on-stone scrub sponge or a blue Scotch-Brite pad (other pads are too harsh on stone), or nylon brush (like grout brush we include with Granite Gold Grout Cleaner®). Let it sit for 15 minutes and rinse with water. Alternatively, place a clean paper towel over the stain and pour a solution of 3-4% hydrogen peroxide onto the towel to the point of saturation. Allow this to sit for 24 hours before wiping away and rinsing the area with water. Repeat as needed. Do not mix bleach or hydrogen peroxide together, as this will create a toxic gas. Best to avoid mixing any household chemicals. After either of the above steps, it's important to always re-seal your stone to protect against future stains.


Clefting is unique to slate due to its structure, having formed layer by layer of various rocks and minerals compacted over millions of years. Clefts make up slate's natural rough feel and appearance, which is what lends itself perfectly for use as flooring. However, this is still a finished look, as the stone's surface has been smoothed down to remove any sharp or extreme features. Chipping or cracks can bring back this sharp clefting, and the problem can compound from there, to the point of needing the help of a stone restoration specialist.

Not Sealing Your Stone

Again, despite slate's tough appearance, it is a porous material, and liquids can and will penetrate the surface of the stone. With that being the case, it's even more important to maintain the protective seal that was applied when the stone was installed.

How to tell when it's time to seal:

As a general rule, it's recommended to re-seal your stone every 6-12 months depending on the area and how much use it sees, but the only way to know for sure is with the water test:

The water test:

Pour water (about 3 inches in diameter) on the surface in several locations and let it sit for 30 minutes. If you see a dark mark or ring, the water is penetrating the stone and it’s time to reseal. Make sure to clean the surface thoroughly before sealing.

How to seal your stone:

Sealing should be done in sections of roughly 3-feet at a time. Spray Granite Gold Sealer® evenly over the section and immediately buff the solution into the slate with a clean microfiber cloth. Be careful to not allow the sealer to dry on the surface, as this can lead to hazing. Once the sealer is applied, work the area with fresh microfiber cloth until the surface is dry to the touch between applications (20 minutes should be plenty). For best results, it's not a bad idea to repeat the process 2-3 times.

Have any more specific questions or concerns on how to care for your slate or other natural stone? Feel free to reach out to our team of Stone Care Experts with more than 50 years of experience at 1-800-475-STONE. Also, be sure to check out our full line stone care products to keep your stone looking great!


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