To Seal or not to Seal?

By Janna Epstein

Granite is a natural creation. One piece of rock is not like any other in the world. This is the one quality that actually makes this stuff so beautiful and in demand. The individuality of each granite slab is what lures so many homeowners into deciding on a granite countertop.

This also means that no two granite slabs have the same absorbent qualities.If all stone came from one quarry, it would be similar, but still unique. For example, Black Galaxy from Brazil may not absorb anything, whereas similar black granite from Asia may be a sponge.It does not matter where the stone is located in your design, it can be a vanity top, kitchen countertop, fireplace surround, island top, or floor tile. If its natural stone, then there is a chance it might need sealing.

What does that tell us? Not all granite or marble will take a sealer. If a stone cannot absorb anything, even an impregnating sealer won’t sink in. Impregnating sealers sit below the surface of stone and deposit solid particles into the pores to coat the individual minerals below. The good news here is that if a sealer won’t penetrate into the stone, neither will a stain. An example is Ubatuba granite: it’s very bulletproof and usually does not require any sealing. Sealer generally does not penetrate this stone and is useless, leaving a hazy film on the surface.

This may come as a surprise to many in the countertop industry. If you go to any home show and ask counter- top salesmen that sell anything other than natural stone what makes their product better than stone and you will always get the same answer. They will all say that stone needs to be sealed every six months to once a year but their countertop surface doesn’t require this “inconvenience”.

The need for sealing every granite, and sealing it often, is a myth and absolutely untrue. These kinds of tales are born from fears and insecurities, or specifically designed to prey on such concerns of homeowners. Everyone loves stone, but there is a certain mystique attached to it that scares the people who know little about it. These scare tactics make granite owners afraid to do anything with their granite stone because if it’s ruined, it’s too expensive to replace. The competition tries to pull away potential customers from getting a stone top by over exaggerating the need for sealing granite and marble countertops.

If this is the only perceived weakness of granite countertops for potential buyers, it’s easy to spread the scare that “all granite needs to be sealed.” It makes sense to them and is a compelling reason for you to buy the competitor’s product instead of granite and other natural stone.

In reality, a small percentage of the commercially available polished stone used for countertops needs a sealer. A low percentage really needs to be sealed because granite is the main stone variety in use, and not all granites are fully absorbent. You can see this on something as simple as a granite boulder in a park or field; after it rains, it doesn’t stay wet. It dries instantly.

Homeowners and fabricators can make the same test. Leave water on a slab for 10-15 minutes and then remove it; if water doesn’t darken the stone when it’s removed, the granite won’t absorb water-based staining material. If you’re shaping an edge on a granite top by working wet, and the stone doesn’t stay dark when the water is removed, it won’t absorb a water-based sealer, either.

You can use a solvent test to see if a solvent- or petroleum-based stain will enter the granite. Simply dab some mineral oil on the slab and leave for 5-l0 minutes. If, after you remove it, it doesn’t darken the stone, neither will a staining agent.

If it does go dark, no worries about damaging the granite with the test; the mineral oil will completely evaporate, leaving the stone its natural color. But, this will tell you that you can use a solvent-based sealer to protect against oil—based stains.

In short, if the granite goes dark with either water or mineral oil, then seal. lf there is no color change alter testing with these two liquids, you do not really need a sealer on your granite countertop.

This test works for granite and almost all other stones, although there’s a caveat here for marble; an impregnating sealer will not protect marble against those nasty water rings and spots.

They aren’t stains, no matter how bad a customer wants them to be stains; they’re etches or corrosion. lt’s a chemical reaction between the calcium in the granite or marble and the acid in the product that caused the etch.

Think of your favorite shirt in the laundry. When you spill water or oil on it, it goes dark. If it stays dark, it’s a stain. If it loses its color, it is bleached out or white, as the dye or color from the thread is gone.

On marble, the surface of the stone is corroded, leaving the stone in its real natural state or its unfinished look. No amount of sealer will bring the color back, it needs to be resurfaced.

It’s also important to emphasize that this applies to commercially available polished stone. When stone is polished, the pores are tighter and restrict the ability of liquids to enter. With honed surfaces, liquids can enter some of the less absorbent stone more freely and therefore require an impregnating sealer.

One of the usual questions to pop up is, once you determine if` you’re going to seal granite, how often to do it? This answer is the easiest: When your countertop no longer repels water or oil. The field test is that, after washing the dishes, a customer starts to notice the stone is darker with moisture and then getting lighter a short time afterwards, it’s time to re-apply (not coat) with the brand of sealer used originally.

Reputable fabricators like All Granite and Marble Crop value their customers and will seal marble and granite that need sealing when installation is complete. They also show the homeowner how to properly seal natural stone so no mistakes are made in the future. Any sealer worth its weight in gold should last you at least one year, even with the most-porous of all marble and granite. As far as lifting the mystery of sealing stone: Seal when needed, and try to use products that don’t require frequent repeat applications. In this case, more is not always better.

Below is an instructional video on how to properly seal your granite counter tops. Remember to always read and follow the directions and warnings found on the label of your chosen sealer.

  • – Walter

    Hi. River White is a pretty porous stone but should be ok when sealed. Use the Oil Stain Remover on your stain ( Then clean the countertops and let dry completely over a few hours. Apply the Superior Zero sealer as in the video above. DO NOT LET IT DRY on the surface – key part. Keep wetting the surface until it doesn’t absorb any more sealer. Then wipe off excess. Let the counters sit for a few hours before use (best to do this overnight). Test in the morning. If it still takes in water (darkens), repeat sealing a week later. It can take two to three applications for really porous stones. The good news is that this is an incremental process, so each time it will take less and less sealer. After that you basically re-seal as needed.

    You’ll be ok. Don’t worry!

  • Confused

    We just had Black Stellaris in a honed finish installed. The distributor said it should be sealed, but the installer said it should not be sealed because it is honed and will take the sealer unevenly creating “spots”. Can you offer any guidance?

  • Peter

    I recommend this Granite Sealer Product from Mr. for sealing countertops.

  • Devastated

    I just installed Mont Blanc quartzite in my kitchen. I chose the slabs ( 3) at the quarry and they were all from the same lot. After they were installed, the slab on the island looks perfect, but the perimeter counters are a darker color (greyer rather than off-white backround). They look like they did when I saw them on a rainy day. They told me to wait 48 hours as they had been wet and they will lighten. It is 3 days later and nothing has changed. Is there something they could have done to the perimeter counters that would permanently darken them? (they sealed all the counters on site at the same time)

  • Peter
  • Devastated

    Hi Peter,
    No you did not do this job for me. I was just asking your advice so I can try to figure out how to proceed. Is it possible that 2 slabs from the lot were darker than the 3rd and I just didn’t realize it? I don’t think so. Did the fabricator apply something that darkened the stone? But then why only on 2 & not the 3rd? They are telling me that these are the slabs I chose and it is what it is. Do I have any recourse? I would greatly appreciate any advice you could give me. Thanks and all the best.

  • Tricia

    I just had a granite counter put in my bathroom. My husband laid a towel he believed was clean on it to hold his tools, but it was actually a rag used for furniture polish or stainless steel cleaner. When he removed it, it left a large square which is darker than the rest. I am assuming whatever was on the towel got absorbed into the stone. The granite originally is a beige, brown with gold. I also noticed that in some places the water beads and in others, especially around the faucet get darker and absorb the water. It eventually dries, but this is telling me that the seal is not consistent. How do I get the stain out and then should I use the Zero product to reseal, so that the entire surface will be consistent in its sealant? Thank you so much!!!

  • Peter

    Devastated, the best thing would be to have pictures of the slabs before and after in order to prove the difference. I am sorry things did not work out for you. Unfortunately there is no way of knowing whether you did not realize the stones were darker and or whether your provider applied something to it to be darker seems unlikely. I would contact management of the company if you are 100% sure it is not the right stone and you could take it up with them. Hope everything works out for you. Best Regards, Peter.

  • Lost

    We are currently deciding between Zanzibar and Platinum granite for counters. The sales person (not you) is trying to upsell us to the Platinum because the Zanzibar is too susceptible to etching from wine, vinegar, etc? We can’t find and specs between the two stones to separate fact from fiction? Additionally we are thinking about White Ice on the island…but now worried about red wine rings, etc. any advice on your sealants for any of these? We’ve had Baltic Brown for 12 years, unsealed, so all of this “worry” is new to us.

  • Peter
  • Peter
  • Anne

    I have UbaTuba granite counters and had a party–someone must have left a glass on the counter. Now i have a light colored ring on the counter. it doesn’t feel etched so i can’t figure out what happened to it. What would you suggest?

  • Peter
  • AC

    Hello, I have Rainforest Green Marble in a smal bathroom on a countertop that has developed white streaks and spots. You can feel a difference in the texture, so something must have etched the surface. What could have caused this and how can I treat it? Is there any way to remove the white? How should I protect the surface from future stains / damage? This is a relatively new problem, as the counters are 8 years old. Any information and advice would be appreciated. Thank you!

  • – Peter
  • Jale

    I purchased a black granite bathroom countertop. As I was cleaning it with water and a wash rag I noticed that black was showing up on the rag. I wiped the countertop several times and it continued. I polished the countertop with Gel Gloss and it the residue on the rag was really black. What’s happening? I also noticed before I cleaned the granite that some areas of the countertop look hazier than other areas. Can you help me?

  • – Peter

    I’m sorry to hear about your problem, did you purchase the granite from us?

  • Jim Z

    Quick question. We have Brosse Blue granite with a “leather” finish as we do not like the glossy/polished finish. Because of this type of finish is sealing required because of this type of finish? Happy to use whatever product you recommend

  • – Peter

    Hello Jim Z,
    We recommend that natural stones are sealed, I would suggest using the Superior Zero Ultimate Stone protector which may be purchased at


    I have a commercial job of installing Beige coloured marble on the floor. The decision I need to take is whether I should use an impregnator on the underbelly as well as the other surfaces. I am installing the Marble with Mortar and using White Cement for buttering. Please help?

  • TheMarbleMan

    Hi, it’s not necessary to use an impregnator on the underbelly since you’re using cement. As long as the surface is sealed you’ll be fine.

  • Cub

    My new white Kashmir vanity stains like crazy, even after using 511 impregnating sealer. The sealer eliminated water staining, but I have stains from my soap dish and from an oil-based cosmetic that spilled on the granite. I’ve only been using it a week and I don’t know what to do. My contractor is dumbfounded and I am trying not to panic. I am able to lift the stains with a putty I bought at the tile store, but I can’t live with a vanity that stains so easily that you can’t even put a soap dish on it. It’s a big
    Bathroom with two large vanities and a granite tub surround. All staining like crazy Any advice?

  • – Jack

    Make sure the stone is cleaned thoroughly prior to applying to the sealer. Some people use acetone to make sure to get all the dirt and oils off of the surface. Our installers use Dupont Bulletproof and Superior Zero sealer; both yield great results. Please let me know how everything goes.

  • Christy

    Hi, could you please recommend a sealer for my granite countertops that will be installed? The Granite is Ivory Fantasy – and this particular lot has a lot of light color in it – like a cream. There are 2 slabs and they were stored in an outdoor yard. I’ve visited the slabs several times, and after it rained they were very grey/dark, so I know I’ll need to seal them. Also the granite place recommended the 1st two weeks a seal it every other day – although from reading I guess I only need to seal it until a water spot no longer changes the granite to a dark color. They are going to seal it the 1st time, but is it okay for me to follow up with a different brand of sealer after they are done – in particular, whatever brand you recommend?

  • Concerned in Colorado

    I recently had Ubatuba installed in my kitchen. Lately when I wipe my counter top down I find spots that look like some type of food dripped & dried on the counter top. When I wipe it off, it seems to peel off the counter top and leave a pit in the granite behind. What is happening? Btw we did not get our granite from you.

  • Ann

    We are building a new house and have installed TYPHOON BOURDOUX (spelling) in the kitchen. What can you tell me about this granite?

  • Amber

    I just bought a home with marble flooring . Couple questions , floor is in good condition and I was told it was sealed 2 years ago . First , how often should I be resealing polished marble floors? Then can I just clean it and Ali a dealer or do I need to strip, seal, buff, Polish etc? If I can just clean and seal will it still have it shines after or do I need to polish it after sealing ? Thank you

  • May

    I treated my granite countertops with a sealant and followed directions exact. It has left a sticky gummy film in many places, and in some places rainbow type streaks. I am scared to death I have ruined my granite. What do I do? It is black granite.