Food-Safe Sealer for Granite Countertops


I just bought some granite countertops, installed by someone who didn't know how to clean them or seal them so they are food safe. How do I do this?


Choosing a food-safe granite sealer is certainly important and a common concern. Most don't know which to use or how to go about sealing granite countertops safely.

food-safe granite sealer bottle sitting on granite countertop surrounded by fruit and vegetables

The short answer is that nearly all impregnating stone sealers are food-safe and approved for use on food-prep surfaces.

But let's back up a step first...

Often sealing granite countertops isn't necessary. Some granite is too dense, won't stain, and just doesn't need a sealer especially blues, blacks, and greens.

So first, you should water test your granite countertops to determine if a granite sealer is even needed.

If testing shows sealing the granite would be beneficial, then I recommend using one of these impregnating marble & granite sealers.

Sealers become inert after curing. It takes a few days after application for a sealer to fully cure, but once it does the sealer is chemically un-reactive and will not contaminate, react with, or affect your food.

In fact, impregnating stone sealers absorb into the stone and work just below the surface of the kitchen countertop to prevent deep absorption of liquids, so food won't even come in direct contact with the stone sealer.

Learn how to apply a granite sealer properly, give it a day or two to cure before using extensively, and you're good to go!

Keep reading below for additional Q & A information on on food-safe granite sealers, natural and green sealers, and sealing other stone surfaces safely.

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Honed Atlantic Stone Countertop Discoloration
by: Anonymous

We bought this stunning light gray Atlantic stone countertop. It’s honed and soft, and really attractive.

We had it sealed by the installer as it was slightly porous. Water test was after 20 minutes it sort of stayed.

We repeated it after about 6-7 months. They left us a bit of the impregnating sealer.

We’ve got it now for about 18 months and we noticed that the stone is quite a bit darker around the sink.

I understand that’s water. Is there any way to dry this so it will lighten up again?

We have 2 cutouts we use for:

1) the coffee machine and
2) for oils and vinegars

After a while, we noticed that underneath it stayed light, but the surrounding area has darkened. So light made it darker.

We are now shifting it around a bit but it’s such a shame that these patches of light have occurred.

We have a waterfall on one side that hasn’t changed color at all!!!

Any advice?

==== Countertop Specialty comment:

Atlantic Stone can look and feel like marble but with properties more like granite (hard, acid-resistant). It forms from molten rock / lava like granite.

The darkening around the sink is probably not being caused by water unless you are using the sink extensively throughout the day every day so basically the area can never dry out.

You didn't say if the darkening is completely encircling the sink, or only on one side, or only around the faucet. This info could help diagnose the cause.

Sure water can absorb into any stone and darken the color temporarily until it evaporates. Most kitchen sinks aren't used enough to where water would cause a persistent darkening.

Also, if the original water test prior to sealing took 20 minutes for the water to absorb, then the stone is not very absorbent to begin with (and probably didn't need sealing).

So, water would have to be left on the surface to absorb for at least 20 minutes before it would darken.

And then you applied a sealer which likely extended that absorption time even more... maybe to 30 or 40 minutes.

FYI about sealing... when a stone countertop is naturally stain-resistant due to low porosity and low absorbency, then a sealer really shouldn't be applied.

Sealers must absorb well in order to work and cannot do so if the stone does not absorb liquids quickly. Also, the sealer must not be allowed to dry on the surface and any residue must be completely removed from the surface or problems (haziness, weird reactions) can ensue.

And once properly sealed, most stone countertops do not need re-sealing for 3-5 years.

This depends on the quality of sealer, of course, and the original porosity of the stone.

But only the most porous of granites (white granite colors) need annual application of a sealer and even then only in some cases. Or if a low-quality sealer is used, then resealing may be needed in 1-3 years.

All you need to do is perform the water test every year to determine when or if resealing is necessary.

Of course, if you were seeing darkening around the sink, etc., then you may have concluded that it needed sealing again.

Other Possibilities - Darkness Around Sink

1. A plumbing leak from the faucet. This could lead to water constantly absorbing into the Atlantic stone from the faucet cutout hole. That would cause a persistent darkening.

2. Glue stains. Accelerants are often used with the glue used to install the countertop slabs. This accelerant can randomly react with granite to cause stains on the surface.

3. A stain from some other substance often used around the sink... like an oil.

It is common to see a dark ring around sinks in such cases, but usually, you'd see similar stains in other areas of the countertop where glue was applied.

To diagnose this you need to stop using the sink for 2 or 3 days. If it is from surface water absorbing, then it should easily dry out in 2-3 days and the staining will disappear with the normal color returning.

If you do this and the darkening doesn't vanish, then it is due to some other issue (leak, glue stain, or stain from other substances).

A true stain occurs when a substance absorbs, does not disappear after evaporation, and cannot be cleaned off by conventional cleaners or methods.

To remove a stain you need to use a poultice like the Granite Stain Remover Poultice.

However, if it's a glue stain, that's trouble. Glue stains are extremely difficult to remove and often are permanent.

If a plumbing leak, you'd likely see other evidence such as water dripping into the cabinet below, etc.

Darkening of Entire Countertop From Light

This can happen and often it is difficult to know exactly why but generally it is something applied to the surface of the stone countertop (like a sealer or a resin) that is reacting to light exposure (usually UV sunlight) and darkening.

Obviously, the areas of the countertop that have been covered by an appliance or whatever don't receive light and are not affected.

The waterfall side is a vertical surface that also won't receive as much light as the horizontal countertop surface.

You can try cleaning the surface with acetone or mineral spirits to remove any sealer residue or resin. You should test in a small more hidden area.

But likely this will not yield positive results or restore the color to the lighter gray of the original Atlantic stone.

Temprature resistance of sealers
by: Leroy

These answers were very helpful I just wondered if anybody knows if there is a maximum heat that the cured sealant can handle.

I bought a huge granite table off ebay to make sweets on but you need to throw the sugar on the table at about 150 degrees celsius.

I am just worried that the extreme heat might cause the sealant /varnish to react with the food.

From what I have read the chemicals are inert once cured but I can not find any specific heat tolerance or specification.

==== Countertop Specialty comment:

Since I'm not a chemist or physicist, I cannot say for certain and I do not have any specific data about the temperature resistance of sealers, but I don't think the temperature will have any effect on the sealer or cause it to react with the sugar.

Here's why...

First, know that sealers set up in the pores of the stone below the actual surface. Stone sealers do not form a film on the surface as varnish does.

So, food on the countertop surface never even contacts the sealer. Liquids that absorb into the stone do, of course, contact the sealer.

However, you aren't ingesting those liquids and once cured the sealer is inert so it doesn't chemically react or contaminate any food or liquid even if it does contact the sealer.

The heat from hot sugar on the surface will certainly reach the sealer molecules but the sealer is chemically inert once cured. Temperature is a factor in chemical reactivity. But if a chemical or molecule is inert, then it still will not react even with high temperatures.

Also, 150 celsius (302 Fahrenheit) is hot but it's not extreme. Granite can take that heat and more from hot pots and pans without issue.

Sealers are engineered to perform under the normal use of a countertop which includes heat and sealers become inert or non-reactive once cured.

Again, I'm not a scientist so I cannot say with certainty how a sealer may react to heat specifically. Sealers will not react with or contaminate food under common circumstances.

However, you may want to contact the sealer manufacturer directly to confirm. Obviously, they have chemists and such creating the sealers and should know with certainty.

Based on my understanding from research and experience, hot sugar should not have any effect on the sealer or cause any reaction to contaminate the sugar.

Also, it doesn't make sense logically that sealers would be approved for use on food prep surface if hot food would cause contamination from the sealer.

But you don't have to apply a granite sealer. Yes, you may get some stains, but if this is a work surface, who cares. And most stains can be removed. Applying a sealer simply eliminates the hassle of removing stains.

Your granite may not even need sealing. Some granites don't need sealing at all. The darker colors (black, blue, green) are typically very dense, do not absorb liquids readily, and do not get stains.

So, if you don't care about stains, then don't bother with the sealer. But if you do apply a granite sealer the high temperature of the sugar should not be an issue in my estimation.

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Food-Safe Sealer for Slate Countertops


What food-safe sealer can I use for a slate countertop? It is machine honed (like a smooth new chalkboard) dark gray in color. it is quarried in Slatington, PA


Most impregnating slate, marble, stone, and granite sealers are "food safe". Stone sealers are made for application to kitchen countertops and food-prep surfaces.

If the slate or granite sealers were not food safe, they would not be approved for use on such surfaces and could not be marketed as such.

Now, of course the sealer itself is not safe to consume, but after it has been applied all the chemicals evaporate and the remaining "cured" sealer is inert... meaning it is not chemically reactive and therefore not a contaminate and safe for food prep areas.

We recommend using one of these marble & granite sealers, which we've found are the most durable and effective.

The above recommended sealers are food-safe and work equally well on slate tile or countertops and on any natural stone or porous surface.

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Sealing Food Prep Areas on Marble Countertops


I'm just starting out making chocolates and need to work with the melted chocolate directly on a marble countertop (or slab) to temper it.

I'm concerned about the chemicals in the sealants getting into the chocolate. I don't really care about the look of the marble.

Can I just leave it unsealed and disinfect it in some way to inhibit bacteria growth?


Impregnating stone sealers do not contaminate food prep surfaces and will not "get into" the chocolate.

First, when a sealer is applied it absorbs into the stone below the surface with all excess and residue wiped clean off the surface itself.

Second once the sealer dries and cures it becomes inert and has no chemical reaction... meaning it does not/cannot interact or contaminate food.

The only reason to apply a sealer is to help prevent staining. So, if you don't care what the marble countertop looks like, then there is no reason to apply a sealer.

Even though most stains can be rather easily removed from the stone, it becomes a pain if you have to do it over and over like you would on a kitchen countertop.

So, no need to seal the marble countertop if you don't care about stains.

Marble doesn't harbor bacteria or promote the growth of bacteria. Cleanability studies of granite & marble have demonstrated that.

Regular cleaning with a good Granite Countertop & Marble Cleaning spray will keep your countertop as clean and safe as possible.

Or you could use a marble-safe Mold & Mildew Remover, which acts more specifically like a disinfectant.

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Sealing Granite Naturally


I need to seal dark granite countertops, but I'd like to apply a more natural sealer without harsh chemicals (more earth-friendly and not as damaging to people).

The kind I found at Lowe's suggests you leave the windows open for 2 days after applying the sealer. Is there a product that does this more naturally? All I can find is natural cleaners, but not natural sealers.


I completely understand what you mean. Many sealers are solvent-based and very noxious during the application process.

Note that once a sealer is applied to the countertop or floor tile and dries it becomes inert and non-toxic.

It's only during the application process when you are directly exposed to the liquid and fumes that a sealer may have an impact on human health.

Recently water-based sealers have been developed to try and minimize the impact on humans and the environment.

Now I wouldn't necessarily call these green sealers, but much better.

I recommend using these recommended marble & granite sealers.

Now, you say you "need" to seal dark granite kitchen countertops...

Have you performed the water test for sealing granite to be sure that it really does need sealing... or did someone just tell you to do it?

Some granite varieties don't need sealing... mainly a few darker varieties. If you test the granite and the results demonstrate that it doesn't need sealing then you should NOT do it "just to be safe."

The sealer must get below the surface into the pores of the stone. If the stone is really dense, the sealer will just sit on top and the residue will leave a streaky mess even after you wipe off the excess. You'll then have to strip off the sealer, and believe me, you do not want to do that job.

If the granite shows signs of even a little porosity/absorbency, then go ahead and seal it.

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Non-Toxic Natural Granite Sealer


I purchase a light-colored granite countertop and I would like to use a non-toxic natural sealer. What is available?


As for natural sealers you could use linseed oil. It was one of the original types of sealers, but it won't last long and will turn yellow with age.

For non-toxic sealers these recommended marble & granite sealers are as good as your are going to get.

Stone sealers will have some fumes during application, but they are not toxic after cured on the countertop.

So, if you are worried about exposure to food... it's not an issue. The reaction that occurs when applying a sealer and after it dries leaves behind molecules that are inert and do not contaminate food.

Most light-colored granites need sealing to guard against stains, but you can simply water test it to find out for sure if you need to seal.

Sometimes you don't have to. If you do... use the recommended marble / granite sealers for the best results and stain-protection.

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What Non-Teflon Based Sealers Are Available For Safe and Effective Use On Granite?


I have a new travertine floor, granite countertop, and backsplash. I am looking for an environmentally safe non-teflon (fluoropolymer) sealer. Do they exist and what are their names. Thanks, Dr. Smith


Flouoro-carbon sealers are pretty standard these days, however, water-based granite sealers like Impregnating Stone Sealer (the water-based sealer we recommend) are less toxic (lower concentration of volatile organic compounds) than solvent-based sealers.

Sealers labeled "non-toxic" may not be actually non-toxic for the environment. Some sealers are marketed as "non-toxic" or "no VOCs" but EPA rules actually target certain VOCs over others, thus a company can claim a product is "zero" VOC and still contain up to 5%.

Or "Green" labels do not necessarily mean that the chemical is completely non-toxic and non-harmful.... just better than the others.

Not being a chemist, I can't definitively answer this question beyond the above explanation. The granite sealer game is won on durability, so the effort is to engineer sealers that protect against all types of oil and water-based stains and last as long as possible.

So far, this entails using chemical compounds that have some toxicity.

However, it is important to clarify and understand that a granite sealer prior to application is toxic, but after applied and cured the VOCs evaporate and the remaining compound is inert, non-toxic, and safe for food prep, etc.

So when talking about "safety" of granite sealers we are not deciding which is safe to use on a countertop. They are all designed to be used on food prep areas.

The issue is that some are less environmentally toxic upon application, so the less-toxic sealers will release fewer VOCs into your home. And this occurs over a short time frame of only a few days to a couple weeks.

Of course, your home is already made with all kinds of materials that emit toxic fumes, which people have developed sensitivities to (sometimes severe).

You could go back in time and use the original sealer... linseed oil, but that would require constant re-application and it tends to yellow.

Also, consider that you do not "have to" seal all stone. By performing a simple test for sealing granite countertops you can determine if your stone even warrants application of a granite sealer.

Many stones are naturally very dense, stain-resistant and should not be sealed.

Also, it's helpful to remember or learn that most stains in stone can be easily removed. It's just that if you have a porous stone for a kitchen countertop, then removing stains can become a nuisance, so sealing makes sense.

But for installations that have a low risk of staining, sealing is very optional and in many cases just unnecessary. This includes some floors, showers, lightly-used bathrooms, or even kitchen backsplashes which get surface splatters, but rarely stains.

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Using mineral oil for a sealer
by: Anonymous

You can also use mineral oil which, does not yellow. This is the same "Food Safe" oil used for wood butcher blocks.

==== Countertop Specialty comment:

True... mineral oil "could" be used although oil of any type will stain or darken the color of the stone, which is usually not desired except on honed surfaces.

Mineral oil has been commonly used to darken soapstone countertops, but it must be re-applied very frequently to maintain the color.

Relatively speaking mineral oil is a rather ineffective stone or granite "sealer" providing some protection against stains from water-based substances, but really no protection against staining from oil-based foods.

Oil also tends to attract more dirt and grime. Honestly, if my choice was to seal with mineral oil or leave the stone un-sealed.... I'd leave it un-sealed.

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Granite Sealer Chemical Odor Sensitivity


I am hypersensitive to chemical odors and I would dearly love to have a granite countertop. What are the sealers made of? Do they off -gas and for how long?


Nearly all chemicals have an odor and some are going to bother people more than others.

Granite sealers are made using either a water base or a solvent base. Solvents are volatile and will off-gas until evaporated at least.

Water-based sealers still have some odor, but not typically as strong as solvent-based sealers.

Usually you will notice an odor only for a couple days or less. However, I'm not a chemist and it is possible that off-gassing occurs with all types of granite sealers or other chemicals longer than your average human would/could actually smell.

So, someone with odor sensitivity may notice it far longer than typical.

The impregnating sealers we recommend represent both water and solvent-based sealers.

There are arguments for both types although many (and in the future possibly all) are going to a water-base since solvent chemicals are more damaging to the environment.

But you don't have to worry about it!

There are plenty of granite colors that don't need a granite sealer because they are dense with low absorption rates.

Such granites are naturally stain resistant and do not need sealing.... in fact couldn't be sealed even if you tried... the granite sealer simply won't absorb and nothing else will either.

These are the most bullet-proof surfaces you can install... highly recommended.

In your situation, I'd choose a dense granite that does not need sealing.

I know you've read that "all" granite "must" be sealed, but that's just marketing mumbo jumbo from quartz countertop and granite sealer manufacturers (trying to sell their product) and from poorly informed stone salespeople, etc.

It's simply not true... many granites and many stone types never need sealing.

That's why you should always perform the water test for sealing granite on a sample taken from the granite slab you are considering purchasing... or when trying to determine if an existing installation needs sealing / re-sealing.

This test will tell you how absorbent a stone is and whether or not it needs sealing or if it even can be sealed.

You should also perform the "Lemon Juice Test" to weed out the rare granite that reacts to acids. Some black granites are appearing in the marketplace now that will etch, so you have to be on the lookout... don't want those.

Most of the granite colors that don't need sealing are on the darker side, but you still have lots to choose from. This is the way to go if you want to avoid applying a granite sealer.

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Green Granite Sealer: How yellow does linseed oil go?
by: Sally

I am thinking of sealing my sandy-coloured granite benchtops with linseed oil.

North-east facing windows run right around my kitchen so it's very light and the benches are in full sunlight.

How yellow does linseed oil go? And how often do you have to reapply it (are we talking every few months or every few years?)

I'm worried it might go more and more yellow with reapplication, but I'm looking for a natural green granite sealer.

Thank you

==== Countertop Specialty comment:

Well, first consider that your granite countertops may not need a sealer at all. It's a bogus myth that "all" granite benchtops "must" be sealed.

Many do benefit from sealing to help prevent staining, but many granite varieties are very dense with super-low absorbency and never need sealing (... in fact, cannot be sealed).

So, first you should perform the water test for sealing granite (see links above this page) to determine if application of a granite sealer is even necessary.

Regarding linseed oil as a green sealer.... It's really impossible to estimate the "degree" of yellowing that could occur. In general, oils will turn more yellow over time.

And they will likely turn yellow more quickly in the areas that receive the most sunlight, so you'll end up with some areas more yellow than others.

Also, linseed oil is only effective against water-based liquid absorption. It won't stop oils from absorbing.

It would need to be re-applied every 6 months to one year.

Typically linseed oil is mixed with solvents (which are not "green") to speed drying time... otherwise it takes a long time for straight linseed oil to dry.

I certainly respect your desire to use natural "green" products. I guess the question you need to answer for yourself is what are you willing to trade off to use a green stone sealant.

To accomplish your "green" goals you'll have to use straight linseed oil (without mixing with solvents) as the granite sealer. This will require a much more difficult application and longer drying time.

Also, you'll need to re-apply the oil frequently. It will likely turn yellow and only protects against water absorption.

So, much more work, trouble and far less effective. You may find that a better compromise is to use a permanent bonding sealer like SenGuard .

It isn't a green granite sealer, but it is much more green that standard sealants.

Why... well, it requires very little (by volume), only needs one application vs. repeated applications like all other sealers, and provides excellent protection against all liquids (oil & water).

This may be the best compromise for sealing granite countertops. Since you only need to apply one time it is far more "green" than sealers that need repeated re-application.

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