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What Is A Concrete Sealer? (A Simple Guide for Choosing Concrete Floor Sealers for Your Project)

Concrete floors have risen in popularity recently because of their affordability, versatility, and cleanability. Using a concrete sealer will protect your investment and keep your floors looking beautiful and clean for longer. This article explains the different types of concrete floor sealer and where to use them.

Table Of Contents

  • Why Should You Seal Your Concrete Floor?
  • What Happens To Your Floor If You Don’t Seal Concrete?
  • Different Types Of Concrete Sealers
  • Common Problems With Average Concrete Sealers?
  • Which Type Of Concrete Sealer Is Better?
  • How Long Do Concrete Sealers Last?
  • What Are The Best Practices For Keeping Concrete Floors Clean?
  • Repairing & Resealing A Concrete Surface

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A concrete sealer is a liquid solution used to protect and visually enhance concrete and increase floor safety. CoverTec’s premium line of concrete sealers is suited for a wide range of applications, from strengthening industrial warehouses to sealing residential basements – and all the concrete floors in between – with superior quality protection. 

Why Should You Seal Your Concrete Floor?

The primary reason to seal concrete is to protect floors from damage like abrasion, staining, freeze-thaw, and salt attack. It is vital to keep fluids and chemicals from getting into the concrete and damaging it.  Sealing will extend the life of the concrete and therefore maintain its functionality for longer. 

Concrete sealer can also be used simply to beautify floors, increase the shine, and enhance the color, especially decorative concrete. Lastly, sealers can be used to put some kind of anti-slip treatment onto the floor – think of a wet concrete driveway or a concrete pool deck.

What Happens To Your Floor If You Don’t Seal Concrete?

If you don’t seal your concrete, you’re likely to run into many problems. Remember that concrete is a very strong, durable material, but it is still porous. Concrete has capillaries and pores that will allow dirt, mold and mildew and moisture to creep in. 

Freeze-thaw attack is a large concern for unsealed concrete. Unsealed concrete sitting outside in a cold climate is subject to water getting inside and freezing. The dangerous thing to remember here is that when water freezes, it expands. This expansion can cause cracking, pitting, and spalling, which will all be left behind in the concrete when the ice thaws. That freeze-thaw action is extremely damaging to concrete.

What is Pitting and Spalling In Concrete?

  •  Pitting describes the small holes, or pits, that appear from localized wear on the surface of concrete. 

  • Spalling is the term used to describe when the concrete surface gets cracked and then breaks off in sheets or flakes.

It is also very important to seal out corrosive chemicals. Things like deicing salts or chlorides from the ocean can get into the concrete. And if it’s reinforced concrete, those chlorides will attack the rebar or the steel reinforcement, causing it to corrode, expand and crack, and even spall the outer concrete. In warehouses and garages, abrasion from heavy traffic, machines and wheeled carts will also wear down the concrete over time. 

So to protect your floor and your property, use a specially designed sealer for your specific floor. Sealing will also make floors easier to clean and maintain. If you don’t seal, you are reducing the durability and longevity of your concrete floor.

Different Types of Concrete Sealers

There are two general categories of concrete sealers: topical sealers and penetrating sealers. Within those categories are the two types of sealers: water-based and solvent-based.

Water vs Solvent Sealers For Concrete

Concrete sealers are developed as either water-based or solvent based but there are a few key differences. 

The purpose of a solvent in a sealer formulation is to be the carrier agent for the sealing ingredients. The solvent dilutes the sealer and makes it spread easier and soak into concrete when applied, leaving behind only the polymers on the surface as the solvent dissipates.  The downside of solvent-based sealers is that they are hazardous (flammable), have a strong odor, and release harmful fumes into the environment. As modern technology has improved, we can now use water as our “solvent”  for our concrete sealers instead of noxious solvent chemicals.

There’s a lot of advantages to using a water-based sealer. The water itself is more environmentally friendly, but there are no flammability issues and far less odor, so they are safer to use indoors. Water-based sealers are also less moisture sensitive and tend to keep their shine for longer. 

Chemical solvent-based sealers can give a very good shine or enhancement to a surface but just don’t last as long. 

Here at CoverTec, we formulate mostly water-based products for our customers, the end-user benefit, and our factory’s staff and workers. We focus more on water-based products because they’re greener and less moisture sensitive. 

Topical Sealers vs Penetrating Sealers For Concrete

What is a Topical Concrete Sealer

Topical sealers form a clear film over the top layer of concrete, providing the best physical barrier for the surface. This clear protective film stops the ingress of things like moisture, chemicals, dirt and debris, and stains (like machine oil) from getting into the concrete. 

Acrylic vs Epoxy vs Polyurethane Sealers On Concrete

Acrylic Concrete Sealers

 The main chemistries available for topical sealers are acrylic, epoxy, or polyurethane, which can be water-based or solvent-based. Epoxy sealer do not have good UV resistance so are used mostly for interior applications.  Acrylic concrete sealers can be used interior or exterior and are typically a single component product. There’s no mixing involved and they tend to be easier to apply and dry faster. Although the acrylic polymer is generally not as tough or water-resistant as the polymers in urethane. If your key focus is shine, then a clear acrylic sealer will certainly do the job.

Our premium acrylic sealer, CoverSeal AC450, is perfect for concrete, particularly for projects that require a turnaround. It is a very stain and wear-resistant acrylic sealer that dries in 20 to 30 minutes. Apply multiple coatings for a very high shine. 

Polyurethane Concrete Sealers

The best performing water-based urethane sealers usually come in 2 parts. That means mixing an ‘A’ and a ‘B’ together. Those 2 parts will chemically combine or crosslink, to form a much tougher polymer on the surface of your concrete.  2 Part polyurethanes are much better on concrete for stain protection, wear-resistant, and water resistance.

The CoverShieldU140 is an excellent choice for garage or wear house floors.  For commercial applications like food hall lobby entrance or restaurant the Covershield U100.  If you want a very high shine for a decorative concrete then the StrongSeal Plus Gloss finish is an excellent choice.

So both acrylic and polyurethane can make good sealers depending on what you’re looking for with your concrete project. But the truth is that the  2 Part polyurethane concrete sealers are more durable with longer-lasting results. The trade-off is that they come in 2 parts that you have to mix carefully (an extra step), and they cost more and take longer to dry.

Epoxy Concrete Sealers

Epoxy concrete sealers are extremely tough. These are great for concrete surfaces with high exposure, like warehouses and delivery centers with both heavy foot and vehicle traffic. Using epoxy as the base of the sealer makes it very chemical and moisture resistant.

CoverShield E900 CoverShield 400 WB

What is a Penetrating Concrete Sealer

The other type of concrete sealer on the market is called penetrating sealer, sometimes referred to as impregnating sealer. These penetrating or impregnating sealers soak into the concrete and repel moisture, dirt, and stains.  These products work by lining the pores and capillaries inside the concrete with a highly repellent film.  As these products are less of a physical barrier and more of a repellent shield, they typically are invisible. You can’t see them on the surface like a film-forming sealer, so they don’t change the appearance of the concrete. A penetrating concrete sealer is the better floor solution for those who want the protective benefits of a sealer but without a change in the appearance of their concrete.

Silanes/Siloxanes vs Fluorochemical Sealers On Concrete

Two of the most popular chemicals used for penetrating sealers are silanes/siloxane emulsions and Fluorochemicals.

Both these products are excellent water repellents, mold resistant and salt resistant.  The fluorochemical, however, will also repel oil-based contaminants  ( motor and food-based oil) and are therefore much more stain-resistant.

Penetrating sealers can come as solvent or water-based and again, the same issues apply concerning solvents.  Namely, flammability, fumes, and odor.

Examples of water-based penetrating sealers would be 

CoverSeal Pen 50 silane siloxane emulsion

CoverSeal Pen 55 fluorochemical

CoverSeal Premium fluorochemical for maximum stain protection

What Are Some Common Problems With Average Concrete Sealers?

In our experience, we’ve heard a lot of complaints and found key problems with the standardized low-cost concrete products on local store shelves.

We’ve found that the number one problem with these standard sealers is that they’re very moisture sensitive. This means the sealer will do what we call “water white” (turn white) in the presence of moisture. This moisture could be coming up from the ground or a damp mark being left on the surface of the sealer. Think of a wet bucket or a wet cup: move it and you’ll see a white ring in its place. 

We found that these standard sealers are designed more for their appearance than durability. So it will add a nice shine and sometimes polish up easier because they are softer, but the trade-off is that they are more easily stained. They are not as durable or water and oil resistant as our products. Those standard sealers are more easily scratched as well.  Some of these lower-cost sealers will even turn yellow because they’re not designed to be very UV resistant, whether inside or outside.

When it comes to vehicular traffic, like on a garage floor or a warehouse, those softer resins in the sealer might be pleasing to the eye, but soon you’ll get things like hot tire pickup. This is when the car rolls in and it leaves tire marks in the sealer or lifts up the sealer coating altogether.

With average low-cost solvent-based sealers from the local home improvement shop, you might get a high sheen for three or four months, but by the time you get to nine months, the shine of the sealer has disappeared because it’s just not a quality product. They reduce the price by reducing the amount of active solids in each product, leaving only 12-15%. CoverTec’s products have almost 50% active ingredients. 

It is also important to note the average sealers’ VOC (solvent content). High VOCs will mean high odor, fumes and highly flammable! VOC is the acronym for volatile organic compounds. Always look for a sealer with little ( less than 100 g/l) to no VOCs.

Which Type Of Concrete Sealer Is Better? | How Will You Use Your Floor?

The type of sealer you should choose – whether it’s a penetrating sealant or a topical seal – will depend on many things. Think of the exposure conditions. Is it for an interior or an exterior surface? Is it a smooth or a rough surface? Are you looking to change the appearance of the concrete surface? 

If this is an outdoor floor, and you are concerned about UV resistance (or better: the infamous yellowing over time due to poor UV resistance) and slip resistance, then penetrating sealers are the best choice. This being said, as topical sealers form a protective film, they change the surface characteristics of the concrete, increasing slipperiness when wet. So in exchange for a new glossy finish, a topical sealer could make the concrete more slippery. 

If you are looking for no change in the appearance of your concrete, then the penetrating sealers are a good choice for this as well. But in contrast, a topical sealer would work better if you are looking for enhancement or to create more of a decorative surface. 

In terms of chemical resistance, topical sealers are an absolute barrier. That would provide the best chemical resistance. As for the penetrating sealers, the very top of the concrete surface is still technically open so while they will repel chemicals, stains, and water, they do not form an absolute barrier. So using a penetrating or impregnating sealer, you give up a little bit of physical protection, but the trade-off is that they don’t change the appearance or surface texture.

It is important to note that topical sealer used on concrete in an exterior environment would require more maintenance as that film is exposed to the elements. It will require more maintenance and ultimately re-coating than a topical concrete sealer used inside. On the other hand, the penetrating sealers are in the concrete surface and are not exposed to the same level of weathering. There’s nothing to lift or peel, so penetrating sealers tend to require less maintenance. 

How To Apply Sealer On Concrete

Applying sealer to concrete floor follows the same process as painting and with the same tools. Clean and prepare your workspace and equipment, and roll the sealer out onto the concrete. Check out our in-depth tutorial on how to apply concrete sealer to learn the full procedure. Concrete sealer is easy to use for both contractors and homeowners. 

How Long Do Concrete Sealers Last?

How long a sealer lasts on concrete depends on the exposure conditions and the chemical nature of the sealer itself. The amount of active solids plays a very big part in determining the durability and longevity of the sealer. It is the additives that help with adhesion and help with the way that the sealer lays or spreads out over the concrete.  All these factors are part of the formulation that will dictate the overall durability of the sealant. 

Here at CoverTec, we formulate with high solid products, and using some of the latest state-of-the-art resins. In doing so, we have a much higher solids ratio than you would find in the average DIY home improvement store. 

The exposure conditions greatly impact the longevity of your concrete sealer. If you are exposing a sealer to high traffic or chemical weathering, then those factors will affect how long the sealer lasts.

This topic circles back to using sealers formulated to have higher solids contents so they won’t wear or deteriorate as fast under those harsh exposure conditions. Most of our products were originally designed for professional/commercial use, but because they are so user-friendly and easy to apply, you can use them in residential projects as well.

For residential applications, our CoverTec concrete sealers last about three to five years. If it’s a high traffic area (like an entryway), that may be a little less, but three to five years is typically where we land with most of our sealers. In a commercial application, a sealant may last two to three years. We do have heavy duty industrial grade sealers, like our U140, so even in a commercial or industrial environment, we anticipate around five years for that sealer. All of our products have good durability. And although nothing’s indestructible, if they’re maintained, if they’re cleaned with the right types of cleaning protocols, you can make your concrete sealer last for many years.

What Are The Best Practices For Keeping Concrete Floors Clean? | How To Avoid Damaging Your Concrete

Now that you’ve carefully sealed your concrete floor, it’s time to learn how to keep it clean. Using a good sealer will decrease your maintenance and shorten cleaning time, so now, the only focus is to keep the concrete clean and the sealer intact. 

  1. Use protective mats wherever possible

  2. Clean up spills ASAP

  3. Avoid using harsh chemicals

This is a quick list of the 3 top tips for keeping your concrete clean. Keep reading for more important details.

To limit the need to clean concrete in the first place, you’ll want to try and keep dust, dirt, and sand to a minimum. Those are the things that can scratch and wear down the surface. So, regularly dust mopping, vacuuming, or simply capturing that sand and dirt before it enters the building is very important. 

The use of entry mats is a good way of keeping down that dust and dirt, regardless of whether you’ve got a law firm in a commercial building or a family of four at home. In colder climates, you should be wary of deicing chemicals and salts. Those chemicals can easily get inside by means of foot traffic in the entryway or rolling tires through the garage and can all impact the sealer and the concrete itself. 

To monitor contaminants but not damage the sealer, we recommend light but frequent washing/cleaning of the floor. Clean up spills as soon as possible. Use a simple mop and bucket or even things like auto scrubbers to clean and extract the residue. 

Avoid using harsh chemicals. You shouldn’t need to use harsh chemicals because your floor is now sealed! Things shouldn’t be sticking to the sealer, much less penetrating it. Don’t use bleach, ammonia, or highly acidic cleaners. Use cleaning products that are more neutral-based, like microbial cleaners. 

Our Emerald Floor Maintainer is a very good cleaner, containing enzymes that will break down grease and dirt. But it’s not a high pH product, it is actually a low, almost neutral, pH cleaning solution. Our concentrated surface products can be diluted with only 1 or 2 ounces per gallon of water. 

Make sure that after mopping and cleaning to extract the residue, so it won’t sit and dry on the surface. If you are in a large commercial area using an auto scrubber, use it in combination with products like our Emerald Floor Maintainer. If you are in a residential setting, we recommend a microbial cleaner like our CoverClean HC or AE to clean the surface of all residue and then allow it to air dry. 

The same rules apply: use only gentle cleaners. You can even use simple green or dishwasher detergent diluted in water to clean concrete.

Understand that using very harsh chemicals like bleach will significantly reduce the repellency of concrete sealers. As the name describes, bleach or chlorine bleach will indeed bleach your concrete. This will whiten and greatly increase the pH of that surface. This being said, they can dull the surface of a glossy sealer. A pH burn can damage the sealer itself, breaking it down. If that’s done repeatedly, the sealer will lose its integrity and start to peel and lift off the surface. 

Remember that with penetrating sealers, the very top surface of the concrete is still technically exposed and can be damaged by the low pH acidic cleaners. If they’re eroding the concrete, they’re also removing the sealer. Because of the danger of pH burn, avoid high pH products and low pH ones, as they both will erode the sealer. 

Pressure washing is a great way to clean a large concrete slab or a warehouse floor. Just be mindful that you are not using it so strongly that it will damage the concrete. If the power is too strong, it will cut into a topical sealer and cause lifting or peeling. In a penetrating sealer, it might etch or remove the very top of the concrete. Control of that pressure lies in the tips, the width of the spray, and the distance from the nozzle to the floor. Don’t use a pencil or other extremely narrow tip to pressure wash a sealed floor. 

Use a wider fan with less pressure and let the cleaner do the work. Let the degreaser or the microbials,  break down the dirt, oils, and other contaminants. Afterward, you only need to rinse them away. Only use higher pressure when deliberately trying to deep clean the surface before resealing.

Repairing and Resealing A Concrete Surface

The same process applies to both topical sealers and penetrating or impregnating sealers for isolated repairs. Instead of repairing a distinct spot on the floor, we recommend you tape out a larger area or section and prep that so it is easier to blend in the affected area.

To prep the surface, existing sealers need to be scrubbed or lightly sanded. Again, clean and extract the residue, allow it to dry, and then reapply a thin coat.  If, after 15 minutes, all of the fresh coat hasn’t soaked in, just wipe up that excess.

When it’s time for the concrete to get a completely new coating, like after a handful of years (depending on the product and the level of exposure), you will still follow the same procedures. Start with sanding or scrubbing the concrete surface with a black pad or 220 sandpaper and then make it clean and dry before resealing. (You can also use machines like floor buffers with the pads underneath to assist with that.)

The purpose of the sanding and scrubbing is to scuff the area and make it dull with micro-scratches, increasing the porosity and absorption of the concrete. That’s also a great way to rejuvenate penetrating sealers with a little fresh coating, whether the concrete is inside or outside. 

For exterior surfaces, in this case, concrete, we can employ pressure washing to help with the resealing process, as previously mentioned. For example, if you have a sealed concrete driveway and it’s time to reapply a coat, then you can use a pressure washer and degreaser, like our SurfaceClean or CoverClean HC.

Allow the concrete to dry, then reapply and rejuvenate an existing sealer.

Now You Know Your Options For Concrete Sealer

We hope our detailed work has given you the proper insight into what exactly concrete floor sealer is, the different available types, and how to determine which type is best for you. 

As always, if you have any questions about which product is the best for your unique situation, call us at: 754-253-3401

Bonus Concrete Topic: What's The Difference Between Concrete and Cement?

It is a common misconception that concrete and cement are the same and that those two words can be used interchangeably. However, the truth is a little different. These terms are related, but concrete and cement are not the same things.

Cement is a manufactured product generally made from a mixture of limestone, clay, shale, and sand. Mixing cement with water makes for the perfect binder for mortar and concrete.

That is the difference: cement is an ingredient in concrete. So: concrete is cement-based, mixed with water and aggregates like sand and gravel. 

About Our Expert | Charles Idowu

Charles Idowu started his career as a civil engineer in 1983 in the UK. After achieving his MBA and his Chartered Engineer qualifications, Charles quickly became the waterproofing and coatings expert for a renowned British construction company. His international work landed him in South Florida, where he combined his engineering experience and passion for business to start CoverTec Products.

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