The best brick sealer to use on brick is a water repellent sealer. Water repellent sealers will penetrate into the brick and chemically react to form a hydophobic barrier within the pores. Water and other liquids will bead off of the brick, reduce damage and deterioration caused by water absorption such as cracking, spalling, pitting, freeze thaw damage, mold and mildew growth, and efflorescence.
The two main types of water repellent sealers are siliconate water repellent sealers and Silane-Siloxane water repellent sealers. Siiconate water repellent sealers are rarely used to seal brick because they can leave behind a visible white surface residue that can't be removed. Silane-Siloxane water repellent sealers don't leave behind a white residue on brick, and they won't change the look or color of the brick. Silane-Siloxane water repellent sealers are the best type of brick sealer you can use.
The Armor SX5000 and Armor SX5000 WB both offer the same list of benefits and last for the same period of time. The difference between the two is simply the carrier. The SX5000 is suspended in solvents and the SX5000 WB is susspended in water. The SX5000 WB is very popular for sealing brick because it has a larger molecule size, but most homeowners and even contractors can't tell the difference between brick sealed with the SX5000 and brick sealed with the SX5000 WB. Which type of brick sealer is the best sealer for your brick will depend entirely on whether or not you prefer water or solvent based sealers.
A second type of penetrating sealer is a silicate concrete sealer, also known as a densifier. Densifiers penetrate into the brick where they chemically react to form a calcium silicate hydrate (CSH) barrier within the pores. Densifiers help to reduce the size of the pores, therefore increasing the density and surface strength. Densifiers can be used on brick, but should be applied in thin light coats. If a silicate sealer is over applied to brick, the CSH crystals can form on the surface and once formed, can only be removed if the top layer of the brick is removed.
A third type of brick sealer is an acrylic sealer. Acrylic sealers are designed to provide brick with a wet look, low gloss, or high gloss finish. Acrylic sealers can be applied to concrete bricks, but red clay bricks or Chicago bricks may experience issues. Acrylic sealers are sensitive to moisture and red clay bricks and Chicago bricks allow for large amounts of moisture to pass through. If moisture is present during the time of application, or if moisture becomes an issue, it will caused the acrylic sealer to blush or delaminate (turn white). If you are considering applying an acrylic sealer to red clay brick or Chicago bricks, you should consider applying the acrylic sealer to a test area first.
How you apply a brick sealer will depend on the type of sealer used. Regardless of which type of brick sealer used, you want to make sure that the brick is completely dry. If water or a pressure washer was used to clean the brick, you want to give the brick at least 24 hours to dry. Water or moisture presence can result in sealer failure, coating failure, or staining. Once the brick has been cleaned and allowed to dry, then you can proceed with applying a brick sealer.
While it is always important to follow the directions provided by the manufacturer, here are a few tips: