What Are the Different Types of Topical Concrete Sealers and Coatings?
Posted by The Concrete Sealer Guy on Apr 26th 2016
What Are the Different Types of Topical Concrete Sealers or Coatings That are Available?
Topical sealers or coatings form protective films, membranes or coatings that adhere to the top of a cementitious surface without any chemical reaction taking place between the coating and the cementitious surface. Topical sealers or coatings almost always change the surface texture by reducing the traction coefficient (i.e. slippery when wet) and also change the appearance by imparting a gloss (ex. high gloss, low gloss, satin finish, or matte finish) or introducing a color. There are 5 main types of topical sealers or coatings: Acrylics, Epoxies, Polyurethanes, Polyureas, and Polyaspartics. We will investigate the various types of topical sealers and their characteristics in this article.
Acrylic Sealers are Simple to Apply and Affordable
An Acrylic polymer resin is the main component of Acrylic concrete sealers. Within an Acrylic topical sealer, an Acrylic resin is suspended in either a water or solvent based formulation. Acrylic topical sealers are generally one component systems as opposed to most Epoxy and Polyurethane topical coatings which are normally two component systems mixed prior to application. Acrylic topical sealers generally yield a clear finish and are available in satin, low gloss, and high gloss finishes. Tints or dyes are usually also available to affect a color change on sealed surfaces. Use of tints or dyes generally produces a transparent or translucent finish as opposed to colored Epoxies or Polyurethanes which normally yield an opaque or monotone finish. Acrylic sealers can vary by Volatile Organic Compounds (VOC) level or solid content. Often, Acrylic sealers are used to enhance the beauty of a concrete, brick, or stone surface by offering a sheen or changing the color of a surface. They are also used for protection against water, moisture, salts, some chemicals as well as other impurities. They can also protect against molds/ mildews, dusting and efflorescence, and freeze/ thaw.
Solvent based Acrylic sealers generally tend to be higher performing than water based ones. However, solvent based Acrylics typically contain higher levels of Volatile Organic Compounds (VOCs) which require greater care while using or storing due to flammable/ combustible traits and strong solvent odor. If an environmentally friendly product is more important, water-based Acrylic sealers are your answer, since most water-based Acrylics contain much lower levels of Volatile Organic Compounds (VOCs), making them more green and user friendly. Solvent based Acrylics generally provide a high gloss "wet look" finish and water based Acrylics typically yield a low gloss or satin finish. Solvent base Acrylics generally adhere better to concrete surfaces than water based Acrylics and also normally enhance color better than water based Acrylics. Low solids Acrylics generally tend to be easier to work with but often times require multiple coats to get a good seal. High solids Acrylics typically require a bit more patience to work with but normally only require one coat (possible light second coat) for a good seal. High solids Acrylics are also used by contractors and home builders as a cure and seal to aid in the curing process of freshly place concrete surfaces.
Acrylic sealers can be used both on both inside and outside concrete surfaces. They are typically the least expensive of all topical coatings. They are generally also very easy to apply and as a result are often selected by DIYers for home improvement sealer projects. Since Acrylics only provide a thin protective coating, they age quicker and require reapplications sooner than other topical coatings. Most Acrylic sealers are UV resistant to guard against yellowing but can become brittle with exposure to extreme heat also contributing to their shorter life expectancy. The lifespan of an acrylic sealer is usually only one to three years, on the shorter end for exterior applications and the longer end for interior applications. Projects such as exposed aggregate, pavers or decorative concrete are great candidates for acrylic concrete sealers. For interior floor applications, sacrificial floor waxes are normally applied over Acrylic sealers as part of regular maintenance to further the extend life of an Acrylic sealer. Acrylic sealers can be slippery when wet so applying an anti skid (ex. sand) to the sealed surface to improve the slip resistance is highly recommended.
Acrylic sealers typically require the least amount of surface preparation of all topical coatings. Usually preparation is limited to ensuring the surface is clean and free of dirt, dust, debris, oil, grease, and other contaminants. Profiling a surface through grinding, shot blasting, sand blasting, or scarifying the surface like for Epoxies and Polyurethanes is generally not required. However, depending on the surface, acid etching sometimes may be needed to promote adhesion.
Acrylic sealers are also available with chemical enhancements, such as the addition of Polyurethane, Epoxy, or Methyl Methacrylate (known as MMA). Modifying Acrylic sealers with these chemicals makes the sealers more durable and boosts their abrasion and chemical resistance. Acrylic sealers can also be made with a lower solids content for smooth dense surfaces such as polished concrete to enhance adhesion and to also serve as polish or stain guards for these surfaces.
Examples of Acrylic sealers in our product offering are:
TS200 Acrylic Topical Sealer SB-25 w/ High Gloss (5 gal.)
TS201 Acrylic Topical Sealer SB-25 w/ High Gloss (5 gal.)
TS202 Acrylic Topical Sealer WB-25 w/ Low Gloss (5 gal.)
Epoxy Concrete Coatings Give Durability, Color Changes, & Extended Life
When a longer life is needed in a topical concrete sealer, an Epoxy concrete coating is usually a very good choice. Epoxies typically cost more than Acrylics, but normally have improved durability, abrasion, and chemical resistance. Epoxies form a thicker and more durable protective film over concrete than Acrylic topical sealers. They are available in both one component and two component systems. They are also available in water and solvent based versions. Two component systems generally perform better than one component systems. Also, solvent based Epoxies typically perform better than water based ones.
Epoxies are generally not UV resistant so they can yellow and fade in the presence of UV rays. Consequently, they are used mainly on interior applications such as high traffic floors (ex. warehouse floors, car dealerships, airplane hangers, commercial kitchens, garage floors, basement floors, etc.). However, some premium Epoxies are now available with a UV resistant additive or top coat to eliminate yellowing. Often, Epoxies are finished with a topcoat of Polyurethane, resulting in a more abrasion and chemically resistant sealed surface. Epoxies are typically available in both clear and colored finishes and usually impart a glossy sheen. Epoxy coatings can be slippery when wet so applying an anti skid to the sealed surface to improve the slip resistance is highly recommended. Slip resistance is normally accomplished through a decorative "chip" system that is broadcasted onto the surface after the Epoxy coating has been applied. The chips which are often colored serve to improve traction but are also used to enhance the look of the coated surface.
Most Epoxies are moisture sensitive when being applied so a surface to be sealed should be sufficiently dry. Epoxies typically also are not breathable and could trap moisture leading to failure. Although, there are some premium Epoxies now being sold that are moisture insensitive and may even require the surface to be dampened to help the sealer penetrate into and bond to the surface. Once dried, Epoxies offer outstanding water repellence. It is always best to check for moisture issues and hydrostatic pressure prior to undertaking an epoxy coating project. The success and performance of an Epoxy coating are highly dependent on preparation. For optimum adhesion and long term performance, preparation may involve having to profile a floor especially on very smooth surfaces such as machine troweled concrete. Some times this can be accomplished chemically by using an etching agent such as Muriatic acid. The acid not only can help give the surface a profile but also lower the pH level of the surface thereby improving the adhesion of the Epoxy to the surface. For best results though, profiling the floor is accomplished by grinding, shot blasting, sand blasting, or scarifying the surface.
When improved resistance to chemicals and abrasion is important, an Epoxy or Epoxy/Polyurethane coating system generally is superior to an Acrylic sealer. High traffic floors such as garages, basements, workshops, etc. are ideal candidates for Epoxy coatings. The lifespan of an Epoxy coating is typically 5-7 years although some premium Epoxy systems that employ a Polyurethane top coat boast up to a 10 year life expectancy. Epoxies cannot be used on freshly placed concrete and all concrete must be fully cured prior to the application of an epoxy coating.
Polyurethane Coatings Are Great on High-Traffic Floors and Offer Superior Chemical and Abrasion Resistance
At almost double the thickness of Acrylics, Polyurethane concrete coatings produce a durable and tough coating that offers improved resistance to wear, chemicals and abrasion over Acrylics and Epoxies. Most Polyurethanes also offer improved UV resistance, gloss, color enhancement, and color stability over Acrylics and Epoxies. Polyurethanes also normally offer the benefit of being able to cure at lower temperatures than Epoxies and Acrylics. In addition, they also typically provide better resistance to hot tire pick up than Acrylics and Epoxies. They are a perfect solution for floors that receive a great deal of traffic, for decorative concrete surfaces, and for concrete countertops. Most Polyurethane coatings are UV resistant and can be used on both interior and exterior surfaces. Some Polyurethane coatings are not UV resistant and would only be suitable for interior use.
Polyurethane coatings typically cost more than Acrylics and Epoxies. Like other topical coatings, Polyurethanes are usually available in water or solvent based formulas and vary in VOC level and solid content. They also come in variable sheens, ranging from high gloss to matte finish. Polyurethane coatings normally produce a clear finish but there are some manufacturers that make available color systems. Polyurethane coatings are normally two component systems, although some varieties are just a one component system. While some Polyurethanes can have good adhesion qualities to concrete, many are not as adhesive as Epoxies and as a result are often used as a top coat over an Epoxy. The Epoxy provides a high build and tough and durable primer coat that serves as an anchor for the Polyurethane top coat which results in a more abrasion and chemically resistant sealed surface.
Polyurethane coatings can be slippery when wet so applying an anti skid to the sealed surface to improve the slip resistance is highly recommended. Most Polyurethanes are moisture sensitive when being applied so surface to be sealed should be sufficiently dry. Some products are not breathable and could trap moisture leading to failure. It is always best to check for moisture issues and hydrostatic pressure prior to undertaking a Polyurethane coating project. Like Epoxy coatings, the success and performance of a Polyurethane coating is highly dependent on preparation. For optimum adhesion and long term performance, preparation may involve having to profile a floor especially on very smooth surfaces such as machine troweled concrete. Some times this can be accomplished chemically by using an etching agent such as Muriatic acid. For best results though, profiling the floor is accomplished by grinding, shot blasting, sand blasting, or scarifying the surface. The life span of most Polyurethane coatings is 7-10 years. Polyurethanes cannot be used on freshly placed concrete and all concrete must be fully cured prior to the application of an Epoxy coating.
There are many types of Polyurethane or Polyurethane derivative coatings available today. Below is a summary of the major types that one is likely to come across. Each type has its own unique characteristics and comes with its own set of advantages and disadvantages.
Aromatic Polyurethane Coatings
There are 2 main types of Polyurethane coatings for sealing concrete surfaces. The first type is Aromatic or Moisture Cured (MCU) Polyurethane coatings. Aromatic Polyurethane coatings are normally the least expensive of all Polyurethane coatings. This type of Polyurethane coating is usually a one component system compared to most Polyurethane coatings which are two component systems. Aromatic Polyurethane coatings cure from moisture that is present in the air as opposed to a chemical reaction that takes place between two chemical components. Unless a UV stabilizer is added, most Aromatic Polyurethane coatings are not UV resistant and will yellow or fade over time.
As a result, these types of coatings are best used for interior applications or as a primer or intermediate coat. However, it should be noted that while not UV stabile, Aromatic Polyurethane coatings generally provide better UV protection than most Epoxies which normally are also not UV stabile. Aromatic Polyurethanes have a very low viscosity and depending on the humidity or moisture content in the air can cure faster than other Polyurethane coatings. Due to their low viscosity, they generally also have better wetting, penetration, and adhesion capabilities than other Polyurethane coatings. These coatings typically can have a much higher resistance to heat than other Polyurethane coatings as well as offer better resistance to water and moisture once cured.
Aliphatic Polyurethane Coatings
Aliphatic Polyurethanes are the second main type of Polyurethane coatings and are also the most widely used. Aliphatic Polyurethane coatings are more expensive than Aromatic Polyurethanes. This type of Polyurethane coating is a two component system and the coating cures from a chemical reaction that takes place between the two components. Unlike Aromatic Polyurethane coatings, Aliphatic Polyurethanes are UV resistant and offer better gloss, color stability and weatherability. They also provide improved chemical resistance and long term adhesion over Aromatic Polyurethane coatings. Aliphatic Polyurethane coatings generally have a higher viscosity and longer pot life than Aromatic Polyurethane coatings.
Because of their UV stability, they can be used on either interior or exterior applications. While they provide reasonably good adhesion to properly prepared surfaces and can serve as a base coat, they are also used extensively as a top coat over Epoxies or other suitable primers which offer better adhesion characteristics. Aliphatic Polyurethane coatings are generally offered in either Acrylic or Polyester formulations. The Polyester Aliphatic Polyurethanes generally offer a harder, stronger, and more chemically resistant surface. The Acrylic Aliphatic Polyurethanes typically offer better gloss and color retention. As a result, Polyester Aliphatic Polyurethanes are most often used on high traffic interior or exterior surfaces and Acrylic Aliphatic Polyurethanes on interior or exterior decorative concrete surfaces.
An example of an Aliphatic Polyurethane coating in our product offering is:
TS210 Heavy Duty Oil and Stain Protector for Concrete Surfaces (1 gal. Kit)
Polyureas
Polyurea coatings are often times considered a Polyurethane coating within the concrete industry so we will include them here in our discussion of Polyurethanes. While they possess some of the same compounds (Aromatic and Aliphatic) though, the resins (ex. Polyether, Polyester, and Polyacrylic, etc.) which combine with the Aromatic and Aliphatic compounds to form Polyurethanes are different. In Polyureas, the Aromatic and Aliphatic compounds instead combine with a Polyamine resin to produce a Polyurea. Aromatic Polyureas suffer from the same main drawback as Aromatic Polyurethanes. That is, they are not UV resistant and do not hold color or weather real well with a tendency to yellow or fade. Thus, most Polyureas that are used for coating purposes on concrete surfaces are Aliphatic Polyureas.
Polyureas are the most expensive of all topical coatings for concrete surfaces. Aliphatic Polyureas offer excellent UV resistance and weathering characteristics. As a result, Aliphatic Polyureas are an excellent choice for exterior applications in addition to interior ones. Polyureas provide the highest performance and chemical, abrasion, and impact resistance of all topical coatings. They also offer the best heat and temperature resistance of all topical coatings. Since they have a lower viscosity, they offer superior wetting and penetration characteristics that yields excellent bonding and adhesion. As a result, Polyureas generally tend to offer the best adhesion of all topical coatings and can be used as a standalone coating as compared to many Polyurethane coatings which are commonly used as a top coat.
Polyureas also offer enough flexibility to bridge small surface cracks. As a coating, they suffer from some serious drawbacks though as they are very difficult to use even for the most experienced of professionals due to their very rapid cure times of a few seconds which requires the use of expensive specialized equipment that mixes the two component system at time of release. With the rapid curing times, applying additional coats can also become an issue. Also, correcting for any application errors or mistakes can be troublesome. However, as a coating, their performance is unmatched:
--Rapid curing times significantly reduce downtime in commercial environments and allow environments to be returned to use in hours instead of days.
--Coatings can be applied in extreme high or low temperatures. They are also generally not moisture sensitive and can be applied in environments with high moisture content or humidity. Moisture on surface still can affect adhesion so surfaces should not be wet though. Also, moisture vapor transmission rates that are too high can lead to failure.
--Coatings typically don't contain solvents or any VOCs so they are generally green and environmentally friendly products.
For optimum adhesion and long term performance, preparation may involve having to profile a floor especially on very smooth surfaces such as machine troweled concrete. Some times this can be accomplished chemically by using an etching agent such as Muriatic acid. For best results though, profiling a floor is accomplished by grinding, shot blasting, sand blasting, or scarifying the surface.
Failure rates are higher for Polyureas than other topical coatings due to inexperience of applicators, lack of proper surface preparation, or from poor application methods. Polyureas can be slippery when wet so applying an anti skid to the sealed surface to improve the slip resistance is highly recommended.
Polyureas cannot be used on freshly placed concrete and all concrete must be fully cured prior to the application of a Polyurea coating.
When the maximum resistance to chemicals, abrasion, impact, and temperature are needed and there is a need to return the surface back to use the quickest, Polyureas are likely the best choice. They are ideal for high traffic areas and for protective coatings for decorative concrete surfaces. The life span for polyureas can be 10 years or more.
Polyaspartics
Polyaspartics are a type of Polyurea and also are not technically a Polyurethane but will be included in the discussion here of Polyurethanes because within the concrete industry they are often times considered a Polyurethane. They are officially known as a Polyaspartic Aliphatic Polyurea but Polyaspartic for short. They are less expensive than pure Polyureas but more expensive than Acrylics, Epoxies, and Polyurethanes. Polyaspartics offer most all of the advantages of pure Polyureas but also overcome many of the disadvantages primarily the extremely rapid cure time of a few seconds like with a pure Polyurea. The Polyaspartics are a slower curing Polyurea (ex. five to 120 minutes), which make them easier to apply use and apply. They also normally don't require specialized equipment to apply like pure Polyureas and can generally be applied using the same application methods as most Polyurethanes.
They offer a high protective film build that is extremely tough and durable. Due to their very low viscosity, Polyaspartics offer excellent surface wetting and penetration resulting in superior substrate adhesion. They offer high gloss retention and excellent color stability. They're application surface temperature range is -30°F to 140°F. Once cured, Polyaspartics are resistant to temperatures as high as 350°F. Polyaspartics are the best choice when looking for a coating that is more chemical, abrasion, impact, and UV resistant than Acrylics, Epoxies, and Polyurethanes but is more user friendly and practical to use than Polyureas. Curing time is relatively fast so coated surfaces can generally be returned to service within a few hours instead of a few days like other topical coatings.
Polyaspartics are used as clear coats for high traffic areas as well as for protective coatings over decorative concrete surfaces. Some manufacturers also offer pigmented systems so colors can be added to a surface. For optimum adhesion and long term performance, preparation may involve having to profile a floor especially on very smooth surfaces such as machine troweled concrete. Some times this can be accomplished chemically by using an etching agent such as Muriatic acid. For best results though, profiling a floor is accomplished by grinding, shot blasting, sand blasting, or scarifying the surface. The lifespan of Polyaspartics can be 10 years or more. Polyaspartic coatings can be slippery when wet so applying an anti skid to the sealed surface to improve the slip resistance is highly recommended.
Polyaspartics cannot be used on freshly placed concrete and all concrete must be fully cured prior to the application of a Polyaspartic coating.