Sealing Slate Tile Countertop

QUESTION:

I have a slate tile countertop that I would like to seal and give a glossier look.


Is there a non-toxic natural product (suitable for eating on) that would accomplish this?

ANSWER:

You have a few options for sealing slate all of which are safe for eating on.

One thing though... you can never achieve a truly "glossy" finish on slate countertops like you might see on a marble or granite countertop.

The high-gloss shine you see on stone countertops is part of the stone itself and a function of the stone characteristics.

The super-shiny finish on any stone does not come from a product, but from intense friction on big machines polishing the stone to a mirror finish.

Some stones can be polished to a high-shine, some mildly shiny and others can't at all. Slate is one of those stones that will always have a matte finish.

However, you can add a "sheen" to a slate tile countertop using a special type of sealer or mineral oil for a more "natural" product.

Mineral oil will darken the slate tile and provide a sheen like when the stone is wet, but again it won't by "glossy".

The only problem with mineral oil is that it will make your slate countertop somewhat oily and it will eventually evaporate requiring frequent re-application.

The best solution is to use a recommended Color-Enhancing Sealer, which is designed specifically for this purpose.

The color-enhancing sealer will also give the slate tile countertop a "wet look" and darken the color. Although, it will take several years before re-application is necessary if ever.

Or you could apply one of these recommended impregnating sealers effective for sealing slate to protect against staining, but do not alter the color.

All of the above sealers are designed for use on food prep surfaces and are completely inert and non-toxic once cured.

Sealing Pietra Slate Countertop

by Susan
(Parsippany, NJ)

QUESTION:

I have a dark gray Pietra Slate Countertop. It is about 10 years old and has a few scratches on it. What should I use to reseal it?

ANSWER:

First, you should perform the water test for sealing countertops to see if your slate countertops even need sealing.

Chances are the countertop will need sealing since many slates are porous enough to benefit from sealing.

However, some slate countertop varieties are super dense and couldn't be sealed even if you tried.

Since the absorbency of natural stone can vary dramatically it's always best to test.

If testing shows you should apply a sealer, then use SenGuard Marble & Granite Sealer (the most advanced sealer available) or one of the other sealers found at the "recommended impregnating sealers" link in previous question above.

SenGuard is excellent for sealing slate as well (or any stone).

On the other hand... if testing shows your slate does not readily absorb liquids and really doesn't need to have a sealer applied, then don't do it.

You should not be sealing slate (or any stone) if testing shows it is dense enough not to need it. The sealer won't absorb, may dry on the surface and that just creates a crummy mess that you'll have to strip off.

So, perform the water test and go from there.

Good Luck,
Ryan

Sealing Slate For Cheeseboard

by DeDe
(Ca, (San Diego))

QUESTION:

I am making presents of cheeseboards from slate and have used an impregnator for sealing the slate.

I am interested in making them shiny. Is there something I can put on top that will be food safe?

People will cut cheese on top. Will it scuff to much by being shiny? It is not going to have tremendous wear. Thanks!

ANSWER:

The shine on stone comes from physical grinding and polishing using special abrasives, so there isn't anything you can put on a stone to make it glossy/shiny.

However, with slate (or any honed/tumbled stone) you can apply a Color-Enhancer Sealer (link above) that will give the stone a "wet look".

So, it will not be glossy, but if you get the slate wet.... that's approximately what it will look like. Applying an enhancer will also keep fingerprints from showing or staining the slate with use.

Once applied and cured (48-72 hours), the sealer is safe for exposure to food. The solvent part of the sealer needs to evaporate and the remaining product lies inert below the surface. It won't contaminate food at all.

Removing Sealer From Slate

by Steve
(Bellingham, WA)

QUESTION:

HELP!! I have a slate tile shower that I'm trying to remove the sealer. It looks really crummy...

Getting the sealer off is taking HOURS and HOURS of scrubbing.

I have used 3 different natural stone cleaners/strippers. I can get most of the sealer off the stone but not the grout.

Any ideas or help you could give would be appreciated.

ANSWER:

You'll need to use methylene chloride... a noxious, toxic solvent. Ventilate your bathroom as best as you can before use.

This will usually take the sealer off the slate tile... if there's any left... and should be effective on the grout too, but you may have to sand or grind down the grout and re-grout.

"Usually", but just know that a color-enhancer is meant to be permanent, so you may end up with a splotchy mess.

I don't mean to add to your woes or completely bum you out, but slate tile is not a great choice for a shower.

Yes, I know you see it in magazines and such, but the quality of slate varies so dramatically (from virtually indestructible to a nearly useless, barely solid "stone") that you never know what you will get.

If you happened to get a weak variety, it could crack, crumble and otherwise fall apart with repeated exposure to water.

Don't panic... it may turn out to be just fine and last forever, but if problems turn up you'll know why.

I'm sure this has been frustrating. Once you have it all worked out and whipped into shape I suggest you restore your energy with a delicious potato burrito at Casa Que Pasa!

Good Luck,
Ryan

Removing 511 Enhancer/Sealer from Jade Slate

by Debby MacArthur
(Spring Lake, NJ)

QUESTION:

I have a new house and 511 enhancer/sealer was just applied to my jade color slate flooring. I do not like the results. Color has turned too dark.

Can I remove the enhancer sealer?

No caulk has been applied yet. 511 enhancer/sealer Was applied less than 1 week ago.

ANSWER:

You'll have to strip the enhancer-sealer off the slate tile surface using a solvent... most likely methylene chloride.

If you are lucky you will be able to strip most or all off. However, if you cannot remove all the enhancer, it could leave areas/spots of darker (enhanced) color, which is likely not desirable.

And you may not have much success at all. The enhancer sealer is meant to provide a permanent color change.

When stripping an impregnating sealer this is usually not an issue because impregnators by and large do not change the stone color and having more or less sealer remaining in some spots does not significantly affect future treatments.

I'd recommend performing a test first, by stripping the sealer off the slate tile in a more hidden spot and see what you get.

You'll find instructions for stripping and complete information regarding stone sealers in the All About Sealing e-book.

The only other option would be to have the floor resurfaced, but that could be expensive and problematic as well.

Sealing and Cleaning Slate Floor

by Roger
(USA)

QUESTION:

A silicon based impregnating sealer was used to sealing slate flooring in kitchen and bathroom. It is natural, earthy colors.

How and with what product would you recommend I clean the floor?

Also, would it hurt to use more sealant and would I have to use a silicon based impregnator?

ANSWER:

For cleaning I'd recommend Tile Floor Cleaner concentrate.

Like marble, slate tile can be sensitive to acidic foods and drinks and alkaline cleaning products. The etching left by acids leaves dull and/or light-colored marks on the stone. To avoid this you need to use pH neutral cleaning products.

Tile Floor Cleaner is formulated to be safe on slate floor tile and all stone floors.... it won't etch the surface.

Sealing again is fine if you think it needs it and it may since many slates are very porous and will stain easily.

In fact, some slates are so porous they are nearly impossible to seal effectively.

And you should use the same type of silicone-based sealer for a second coat. Sometimes you can get a bad reaction if you apply a different type of sealer over another when sealing slate or any stone.