When it comes to sealing brick there are a few types of sealers that can be used and a few types of sealers that should be avoided.
Brick Hardeners and Densifiers
Silicates: Sodium and lithium based densifiers penetrate into the brick and chemically react to form a hardened crystalline barrier within the pores. The barrer, once cured, can leave brick with an increased strength and density of up to 45%. There are a few important factors to keep in mind if you want to use a densifier on brick:
- Densifiers offer no other benefits aside from increasing the strength and density of the concrete. Brick sealed with a densifier is still exposed to water damage, freeze thaw and ice damage, and salt damage.
- Brick is very porous and densifiers are sensitive to over application. If a densifier is over applied it will react on the surface, leaving the surface covered with white crystals. These white crystals are identical as to what forms within the pores and they are near impossible to remove without grinding. If you apply a densifier to brick, do so with very light coats.
Water Repellent Brick Sealers
Water Repellents: Water repellent sealers, like the Armor SX5000, are the most common type of sealer to use on brick. Water repellents penetrate into the concrete and chemically react to form a hydrophobic barrier within the pores. Water repellent sealers won't change the look of the brick, but they will help to prevent damage caused by water absorption - such as cracking, spalling, pitting, ice and salt damage, and the growth of mold and mildew. Applying a water repellent sealer is very easy:
- Make sure the brick is clean and dry, free of anything that would prevent proper penetration and abosrption.
- Using a 20 PSI or less sprayer, apply the first coat of the Armor SX5000. If the water based SX5000 was used, apply the second coat while the first coat is still wet; if the solvent based SX5000 was used, you can apply the second coat while the first coat is still wet, or wait up to 24 hours for a more aggressive bead.
- Let dry. Do not let the brick come into contact with water for at least 24-36 hours.
Water repellent sealers can be applied to interior or exterior brick surfaces. One 5-Gallon pail will cover up to 400-500 FT2 in two coats.
Wet Look and High Gloss Brick Sealers
Wet Look-High Gloss Sealers: Wet look and high gloss sealers are the type of brick sealer than many people prefer, but they are also the type of sealer you want to avoid. Wet look and high gloss sealers are acrylic in base and acrylics are sensitive to water and moisture. Brick, which is very porous, allows for large amounts of water and moisture to pass through. If you apply a wet look or high gloss sealer to brick, you chance the risk of peeling or delamination in as little as 2 weeks to 6 months. You can apply a water repellent sealer down first to help increase the life, but with brick there is no way to guarantee or estimate the life of an acrylic based sealer when applied to brick. It is also suggested to apply acrylic sealers to a test area first to test adhesion and life.