Concrete sealers fall into two broad categories: penetrates and film formers.
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Description of Concrete Sealers
Penetrating sealers, such as silanes, siloxanes, and silicates, react chemically within the capillaries of the concrete to shield against moisture penetration and deicing chemicals. Usually they provide invisible protection without changing the surface appearance. They are most commonly used to improve the durability of exterior concrete surfaces subject to corrosion and freeze-thaw damage.
Film forming sealers are the type most often used for decorative concrete work, and they do just what the name implies – form a protective film on the surface of the concrete. Most of them also impart a sheen that highlights the beauty of colored or exposed-aggregate concrete. In the category of film formers, you’ll find three primary types, each possessing different advantages and limitations:
Acrylics. Available in both solvent- and water-based formulations, acrylic sealers are generally the easiest to apply and the most economical. They are widely used on exterior surfaces because they are UV resistant, non-yellowing, and provide good protection against water and chloride intrusion. However, they usually are much thinner than polyurethanes and epoxies, so they wear faster and usually require reapplication sooner.
Polyurethanes. These sealers are also available in water- and solvent-based versions. They are nearly twice as thick as an acrylic sealer and provide excellent resistance to abrasion and chemicals. Bust most polyurethanes are moisture intolerant until they cure. That means if any water is present on the surface when the sealer is applied, a chemical reaction will occur that results in foaming and bubbling.
Epoxies. Like urethanes, epoxies also produce a hard, long-wearing, abrasion-resistant finish. They bond well to concrete and cement-based overlays and are available clear or pigmented if you wish to add color. However, epoxies have a tendency to yellow with UV exposure, so they generally are limited to interior applications.
In addition to straight sealers, which typically must be applied to concrete that has been allowed to cure for at least 14 days, you’ll also find products on the market called “cure and seals” – hybrid formulations that will both cure and seal concrete in one application. Most cure and seals are water- or solvent-based acrylic resins. These products can be applied to freshly placed concrete in lieu of a curing membrane and as a sealer on concrete of any age. Be sure to use a cure-and-seal product that meets the requirements of ASTM C1315, “Standard Specification for Liquid Membrane-Forming Compounds Having Special Properties for Curing and Sealing Concrete.”
Benefits of Our Sealers
Surface Preparation: Concrete surface must be clean and free of all contaminants and water. Do not apply if rain is forecast within 24 hours. If moisture is present or if the surface is not clean and free of all contaminants, the sealer may have white spots and have premature delamination and failure.
Substrate temperature must be no less than 40 degrees F and not exceed 80 degrees F. If applied outside these limits the sealer may not achieve adequate film formation and may have excessive air entrapment, bubbles, blushing or hazing.
Mixing: Stir well before using. Material may separate during long-term storage.
Application: Apply using a 1 ¼” long nap roller cover using long even uniform strokes at approximately 100-300 square feet per gallon depending on porosity and texture of substrate. A Chapin style solvent resistant sprayer is not recommended for this sealer due to high content of solids. Thick or puddle areas may prevent the solvent from evaporating and may be susceptible to moisture intrusion which may cause milky white spots. Applying too thin may cause sealer to prematurely delaminate, flake or wear away. Allow sealer to dry for 24 hours for light traffic and at least 48 hours for heavy traffic. If applying two coats, wait approximately 4 – 6 hours between coats.
Please note: It is always recommended to test the product in a small, inconspicuous area (on the same concrete substrate) for desired results prior to application. Coverage rates may vary for all coatings and substrates depending on porosity, density, texture, etc. If applying by spray method, extended coverage rates may be achieved, but be aware that less material will be a applied and inadequate film formation or performance expectations may be limited.