Sealers for stone (also known as impregnators) are below-surface penetrating sealers, not topical hard shell sealers like those, for instance, that are applied onto wood floors or furniture. They are delivered inside the stone by natural absorption.
Countertops
Seal Granite The Right Way
15 Years and no need to reapply
Some stones absorb more than others. Granite sealer consists of a solid part, or resin, and a solvent or water carrier.
The solid stays in the stone and clogs the pores of the stone to keep liquid stains out. The carrier brings the solid into the stone and then evaporates.
One of the most important phases of the whole sealing process, is the thorough and complete cleaning and removal of any residue from the stone surface. This prevents any alterations to the color or the finish of the stone surface.
See Granite Sealers for suppliers of high quality sealer.
Why should you seal granite? Sealing granite is such a misunderstood practice and misused marketing weapon. It's the result of ignorance in the stone industry and malicious intent by sales people of competing countertop materials.
It's generally believed that when a material is delicate and hard to maintain, it needs to be sealed. The stone industry set out to solve the concerns of staining granite countertops by soliciting chemists to find a sealer for stone. Unfortunately, the chemists didn't know the first thing about petrography.
Granite sealer, the miracle in a bottle, became what I consider one of the most over-promoted, overrated, and over-applied products in history.
See GraniteCarePro.com for professional sealing and cleaning products for your countertops and kitchen.
It should be pretty clear that to work, an impregnator must go into the stone. But to do that, it has to be absorbed by it. Several commercial granites don't absorb anything due to their inherent density. Therefore no impregnator will ever go in.
If you apply it anyway, there's the distinct chance that some of it will remain on the surface of the stone and it will be affected by spills, giving the impression that the stone is damaged.
This damage will appear in the form of "ghost water stains" or "water rings" confused for granite water stains. Some of the best stone surfaces available can be made to look "stained" by sealing them. When in fact, the sealer is what is stained. Do not seal granite counter top stone that does not need it. See Granite Stain Removal for more on this.
Take the lemon juice test
So how do you know if sealing granite is necessary? See the Lemon Juice Test.
Different granites each have their own needs depending on how porous they are. Some granites never need sealer and should never be sealed (black stones especially). Others need several coats of sealer. Granite is very different than marble or limestone, so first make sure you are dealing with granite.
You can test your stone to see if it needs sealer by putting a few drops of lemon juice in an inconspicuous place. If dark spots appear quickly, the stone is potentially a problem since it is reacting with an acid. Chances are it cannot be sealed properly. This is what happens with limestone counters. If the drops take a minute or so to be absorbed, you can protect the top with sealer.
If the lemon juice doesn't absorb at all, the stone does not need to be sealed. Contrary to what you may have heard, sealing granite is not always a necessary part of granite counter care. In fact, the performance of various granites can differ greatly. Some need sealer to prevent a granite stain while others don't.
Many granite companies use poor quality silicon or siloxane based sealers that require re-application every 6 months or every year. These sealers are very common and many misconceptions about sealing granite come from widespread use of them.
We recommend and use a fluorocarbon alphatic resin sealer. Unlike silicon sealers, it will not evaporate or go through any type of natural deterioration. That is why the particular brand we use for all our sealing, MB Stone MB-4 impregnator, comes with a 10 year warranty. Unfortunately, fluorocarbon alphatic resin is more expensive, but you get what you pay for. And in this case it is peace of mind and easy maintenance.
If you're dealing with calcium based stones like limestone or marble, no matter what sealer you use, you cannot avoid the damage caused by acids. Anyone who tells you differently is wrong.
Is sealing granite easy?
Sealing granite countertops is as easy as spray on, let sit, and wipe off. There's no polishing, buffing, or strange applicators. It literally takes minutes. And if you're using a high quality alphatic resin granite sealer, you don't need to keep applying coats year after year.
As a fabricator and installer, we always degreased countertops and gave them their final cleaning with denatured alcohol. Denatured alcohol, it turns out, does wonders for cleaning granite and cutting through film buildup on your counters. The result is the original shiny surface.
Cleaning granite countertops should only be done with specialized cleaners, not Windex or ammonia. The best performing product we have found is MB Stone Care MB-5 Marble, Granite and More Spray Cleaner. We have provided this to all our customers as part of a stone care kit when we install a new countertop and when we show them how to clean granite. See How To Clean Granite Tops.
See Granite Repair for tips and resources to fix damaged and chipped tops.
See Granite Sealers for granite sealers and cleaners.
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As a granite countertop fabricator and installer, I was approached by Angie's List but it wasn't for a paid listing. When dealing with contractors of any kind, quality referrals are your best way to avoid the frustration and hassle. And it's why you should consider a referral source like Angie's List to help you find any kind of contractor, not just granite fabricators and installers.
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What is granite sealer anyway?
Now, knowing that the resin is absorbed for the purpose of sealing the stones natural pores, it stands to reason that an impregnator cannot, and does not, offer any protection whatsoever to the surface of the stone - physical or chemical damage such as scratches or etching by acids.
Granite Countertop Supports & Installation Guidelines
MB-4 Granite Sealer
As professional granite installers, we provide MB-4 to all our customers as part of a stone care kit.
We researched and tested several stone sealers before choosing MB-4. It's been the only sealer we've used for 8 years now.
MB-4 Impregnator/Sealer from MB Stone is hands down the best performing granite sealer we have found.
Why should you seal granite? Granite is a natural product and inherently porous. It can stain.
Many granite companies use poor quality silicon or siloxane based sealers that require re-application every 6 months to a year. These sealers create misconceptions about sealing granite.
MB-4 is a fluorocarbon alphatic resin sealer. Unlike silicon sealers, it will not evaporate or go through any type of natural deterioration. That's why MB-4 comes with a 10-year warranty. MB-4 sealer for granite prevents liquids from being absorbed by all natural stones - marble, granite, travertine, and limestone.
Unfortunately, fluorocarbon alphatic resin is more expensive . . . but you get what you pay for. And in this case, it's peace of mind and easy maintenance. The 32 ounce bottle is a lot of sealer too.
Applied properly, this sealer will last 10 to 15 years and you don't need to reapply before then!
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MB-4 Stone Sealer 32 Oz.