Penetrating Brick Sealers
Under the category of penetrating sealers there are densifiers and water repellent sealers.
Densifiers:Densifiers, usually sodium or lithium silicate based sealers, will penetrate into the brick and chemically react to form a crystalling barrier within the pores. While it never hurts to use a densifier, a densifier is not always needed. Brick is very porous and will absorb large amounts of any sealer applied to the surface. If you over apply a densifier, calcium silicate hydrate will react on the surface and you will be left with brick covered in white crystals. These white crystals can sometimes be removed using a high PH cleaner, but in most cases, once the crystals form they are permanent. If you use a denfier on brick, be sure to apply multiple light coats as apposed to only one or two heavy coats. Other than increasing the strength of brick, densifiers offer little to no other benefits when applied to brick surfaces.
Water Repellent Sealers: Water repellent sealers are the best type of sealer to use on brick. They penetrate into the brick and chemically react to form a hydrophobic barrier within the pores. Once cured, the barrier will cause water and other liqiuds to bead off the surface. Water repellent will not change the look or color of the brick, and they won't leave behind a surface film or coating. They work entirely below the surface from within the pores. Water repellent sealers repel water and by repelling water prevent a variety of issues including cracking, spalling, pitting, ice and salt damage, and the growth of mold and mildew. Water repellent sealers, like the Armor SX5000, can be used to seal brick walls, brick driveways, brick walkways, brick floors, and other brick applications.
Wet Look and High Gloss Brick Sealers
High gloss and wet look brick sealers typically have an acrylic base or acrylic component. Acrylics are moisture sensitive and brick, because of the porosity, allow for large amounts of moisture to penetrate through. When wet look or high gloss sealers are applied to brick that does not have a vapor barrier installed below, will peel or flate anywhere from 1-60 days. In some cases an acrylic will survive longer but it is very rare for an acrylic based sealer to live beyond 60 days when applied to brick. Epoxies and urethanes, which have a stronger bond, have been applied to brick with the same outcome - peeling and flaking. Consider a water repellent sealer that will provide years of service live and will never peel, flake, or fade.