Best Sealer for Flagstone

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Easiest to Use

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Gloss Finish

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How We Found the Best Sealer for Flagstone

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Table of Contents

Buyers Guide – Best Sealer for Flagstone 

The material that flagstone is made of is porous and permeable, which is why only a specific kind of sealer will work on the flagstone and others will not. With the increase in the availability of imported flagstones and setts, homeowners, developers, and contractors alike are contemplating investing in sealants. Sealants offer protection and give the flagstone a finished look. 

However, many argue that sealants are not important or even necessary for flagstones. The idea that new stones should be heavily sealed a myth and marketing strategy of sealant manufacturers. 

If you have no experience using sealants, ensure that the new stone is left the way it is for one year. If the weather conditions during all the seasons in one year do no disrupt the stone and there is no visible fracture on the pavement, you can begin with the sealing process. Before you apply the sealer, ensure that the stone is fully dry for three consecutive days and is thoroughly cleaned. Only then should you apply the sealant you want to use. 

Two main reasons why sealants are usually used is because 

1) the stone is vulnerable and 

2) improving the look of the stone. 

The vulnerability could mean anything from; algae or lichen developing on wet stone; fruit and bird droppings from nearby trees; or the stone being in an area that is rarely dry. All of these conditions can affect the stone which is why a sealant is required to protect it. Secondly, if you have a certain type of stone like the black limestone, constant exposure to UV can harm the stone which is why sealant is applied. You can also apply sealant if you wish to enhance the color of your stone. 

Silane-siloxane water repellant sealers and acrylic sealers are two kinds of flagstone sealers. 

Silane-Siloxane Water Repellant Sealers

This sealer is the best to use on the flagstone. The sealer will not leave behind a surface film that is visible and will not change the appearance of your flagstone. The main function of the silane-siloxane water repellant sealer is that it protects your stone from water-damage by protecting it from within the pores and reducing staining.

This sealer infiltrates into the surface of the flagstone and chemically reacts to form a hydrophobic inside the pores so that the water will not cause deterioration. Liquids like water will simply drip off the surface and not leave a mark on the stone nor will it damage the flagstone in the long-term. Silane-siloxane water repellant sealer will also helo the flagstone to get resistant to fractures. spoiling, freezing-thawing harm, damage caused by salt, efflorescence, mildew, and mold.  When applied to dark-colored stones, the water-repellent sealant may leave behind a white residue. However, this is one of the best sealers for flagstone. 

Acrylic Sealers for Flagstone 

If you want to change the aesthetic of your flagstone, use an acrylic sealer as this will achieve a wet, low, and high gloss finish. Applying acrylic sealers on flagstone is different than applying acrylic sealers for concrete due to the high porosity of acrylic sealers. Without a vapor barrier installed on flagstone, the acrylic sealer will be sensitive to moisture and flagstone allows moisture to penetrate quite easily.

Before you begin to apply an acrylic sealer, test the sealer on a small patch before applying it to the entire surface area so that you can test its adhesive levels and how long it will last. When you do this, apply one thin coat first and then another thin coat over that. This sealer must always be applied in thin layers as it is not formulated to last as high build coatings. 

While acrylic sealers modify and enhance the look of the flagstone while also protecting it, ensure that the sealer you have is compatible with your stone. Applying one coat will stay for quite long but depending on your specific situation, you may need to re-apply the coat every 1 or 2 years. If by any chance, your acrylic sealer leaves behind a white residue or de-laminates, consider going for a water-repellent sealer. 

Our Reviews - Best Sealer for Flagstone

Best Value

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Best Sealer for Flagstone – Best Overall

This is one of the most effective sealers that provide maximum protection against the harshest liquid-based and oil stains. 

With this sealer, you can get your flagstone to look as good as new as it can be preserved for up to 5 years in indoor environments and 3 years outdoors. 

Among its features is that it is formulated with advanced and water-based fluoropolymers. 

It provides coverage for up to 900 square feet and is compatible with limestone, granite, textured marble, travertine, bluestone, sandstone, and saltillo.

Easiest to Use

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Best Sealer for Flagstone – Easiest to use

This sealer will provide you great quality at an affordable cost.

The Essential values sealer is formulated to seal, condition, and finish the most non-resilient hard surfaces such as slate, quarry tile, concrete, terrazzo, brick, sandstone, and pavers.

It is easy to apply, will keep the flagstone moisture-free, and provides high gloss, depending on the application.


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Best Sealer for Flagstone – Budget

Rain Guard Water sealer helps to prevent damage from snow, ice, rain, and can provide protection for up to five years. 

Once applied, it will not change the appearance of the stone and nor will it leave a film on the surface, preventing the stone from efflorescence. What is exceptional about this sealer is that it has UV stabilizers that prevent the stone from yellowing. 

This sealer can be applied with a roller or brush and it is safe for humans, pets, and plants.

Gloss Finish

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Best Sealer for Flagstone – Best for a Glossy Finish

Consisting of 25% solids, solvent-based acrylic prevents the flagstone from yellowing, protects it from UV rays, and does not wear easily.

You can cover approximately 200 square feet per gallon. It will also gove an extremely high gloss finish.

The best feature of this sealer is that you can cure and apply it one day after your flagstone is fully clean, granted that the stone is also dry and spotless.

Beer recommendation

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Best Sealer for Flagstone –  Best beer to drink afterwards.

Well done. You found the best sealer for flagstone thanks to the gang at Cleaning King, you sealed your stones, and now they look brilliant.

You deserve a beer.

After getting down to the ground on a hot day there’s nothing we like better than a refreshing Pacifico Clara.


How to seal flagstones

If your flagstone is newly installed, wait for at least a year for the stone to weather. During this time ensure that you are regularly cleaning the flagstone. Here are a few steps to take before applying the sealer: 


Firstly, clean the flagstone extremely well. There should be no stain or mark left on the surface as this can be next to impossible to remove once the sealer is set in. For basic cleaning, wash the flagstone with soapy water. It does not matter if your water is hot or cold as long as it is soapy water. However, do not use a washing liquid that contains any type of acid in it as it can be harmful to the stone. Scrub the surface well enough so that there is no surface rubble left behind. 

Then sweep away any kind of leaf or dirt you see still lingering around. 

Ensure that the weeds growing from between the flagstone are removed properly. 

Weather conditions 

Before you begin this process, check the weather forecast for the next three days. Applying a sealer well requires the flagstone to be dry for at least 72 hours before application. If there is any sign of rain, delay the task until the next dry weather day. 

5-20 degree celsius temperature is ideal for the application of sealant. Even if there no reason, the weather has to be between these temperatures. The way your sealer turns out in terms of appearance, application, and performance depends a lot on the weather conditions. 

Protective Clothing 

Although sealants are solvent-free and water-based and usually non-toxic, it is still better to take preventative measures than to risk it. Therefore cover yourself in protective clothing, wear gloves, goggles, or any eyewear. If any adjacent objects will be exposed to the sealant, consider covering or masking them as well. 

Remember to not let children, pets, or plants near the sealer area. 


Get a patch test done before applying the sealer just to assure yourself that the sealer is effective and safe to use. This is important because you cannot possibly remove or reverse the effects of a sealer. Use a small brush to apply the sealer on a tiny patch of the flagstone. Leave it that way for a couple of hours and then check if there are any changes on the stone. 

Apply sealant

  • Apply the first coat for impregnation and use a low-pressure sprayer for best results 
  • The stone sealer should be applied at 150 ml per meter square. 
  • While using a low-pressure sealer, apply it in circular motions and consistently for each slab. 
  • Do this for the surface area until no part is left without a sealer. Leave it this way for ten minutes for the stone to absorb it. 
  • Once this is done, apply the second coast after 15 minutes. The sealant should be applied evenly. 
  • Let the sealer dry for at least 2-3 or more before allowing anyone to step over it.

Conclusion – Best Sealer for Flagstone 

The best sealer is the one that caters to your needs. If you are looking for full protection from water and other stains, go for a silane siloxane water repellant for flagstone. This is considered to be very effective. If you want to change the way your flagstone looks, use the acrylic sealers for flagstone as this will provide a glossy finish.

Before you decide to seal the flagstone, talk to an expert, a contractor, or a homeowner who has done this before. They will be able to help you narrow down what exactly you need and how to get it done perfectly.

If you do not feel comfortable doing it by yourself, hire someone else to do it as sealers cannot come off once they are in.

You will need to replace the entire flagstone if something goes wrong. Also, do not do this just because you heard another person talking about it. It completely depends on the stone you have, the weather conditions you live in, and the benefits of sealing the stone. Even without a sealer, keep your flagstone clean, and trim the weeds regularly so that it looks good and does not deteriorate easily.

While each of the sealers reviewed here are valid options, if we were pushed to select our top product, it would have to go to the StoneTech BulletProof Sealer.

Cleaning Kings Choice - Best Sealer for Flagstone

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Best Sealer for Flagstone - FAQs

Stone is absorptive and is usually stained with a footprint, liquid spillages, or even oil. To avoid damage to the stone and to maintain its appearance, a sealer can be applied.

You cannot prevent stains completely but if you spot one, you can clean it easier as it has a longer reaction time.

No, it is not essential but it is wise to use a sealer to maintain the stone in pristine condition. Before you buy a sealer, do your own research about where your flagstone is placed, if it is vulnerable to weather conditions and if you need to apply sealer.

Not all sealers are expensive but it is best if you do not make a purchase based on price. You will find several sealers for as low as $30-40 which are effective as well but read the manufacturer’s description of the product and see if it suits your needs first. However, if you want to see long-lasting results, buy one that has good reviews and ratings.

You will not need to regularly reseal the flagstone but it is advisable to do so every 2-5 years, depending on the sealer you have used.