Brick is very porous and for that reason, most sealers have trouble bonding to it. The best type of sealer to use on brick is a silane/siloxane water repellent. Unlike other sealers, a silane/siloxane is not designed to fill in the pores. Instead, it lines the pores and the surface with an invisible hydrophobic barrier that keeps water and other liquids on the surface. Water will “bead” off the surface coating.
Silicates can be used to strengthen the brick, but not waterproof it. Acrylics should not be used on brick at all because bricks are too porous for the acrylic to develop a bond.
Silane/Siloxane Water Repellent Manufacturers: