When it comes to choosing a professional sealer for sealing stone, brick, or concrete, it is important to first understand the types of sealers that are available. Understanding the types of sealers will help you to determine which sealer is appropriate for your specific applications desired look and finish.
Silicate sealers are ok to use on concrete surfaces, but when used on stone or brick can cause a white crystal formation on the surface. Silicates should only be used on concrete that requires reduced pore size (water or moisture), or an increase in strength (weak or deteriorating surface). Silicate sealers are used as part of the polishing process as well.
Silane Siloxane sealers are the best sealer to use on all types of masonry - stone, brick, pavers, and concrete. They penetrate into the surface where they chemically react to form a hydrophobic barrier within the pores. Silane Siloxane sealers can leave behind a darkened finish, but this rarely happens and is only caused from severe over application. Silane Siloxane sealers are the best type of sealer to use if you want to protect the masonry without changing the look or color of the surface. They help to reduce water absorption, mold and mildew growth, staining, and deterioration caused by water absorption
Acrylic sealers or coatings rely on adhesion and are ok to use on concrete and pavers, but when used on red clay brick or stone can result in delamination (flaking spots or peeling). While acrylic sealers have been proven to work well on aggregate surfaces, if applied to larger stones may result in coating failure. Acrylic coatings are great to use on interior and exterior, vertical and horizontal surfaces because they are cost effective, easy to apply, and will enhance the masonry with a wet look, high gloss, or colored coating. They can be applied with a roller or sprayer, and are very easy to apply and maintain. Solvent based acrylic coatings perform best on masonry because they offer an aggressive bond to the surface, don't need to be screen sanded upon reapplication, darken the surface to bring out dull and faded surfaces, and can be applied in clear or a color enhanced coating.
Urethane coatings and Epoxy Coatings are best to use on interior concrete, but when used on exterior concrete, brick, pavers, or stone, can eventually delaminate and yellow. Urethane and epoxy coatings offer a very aggressive bond to properly applied surfaces, but they are not breathable and are sensitive to increased below surface moisture caused by rain and snow and need vapor barriers for best performance. They are very hard, if not impossible to remove, from brick or stone without grinding the surface. They also require more maintenance to recoat down the road. On an interior surface, they offer many benefits when used to seal garage and shop floors, warehouse floors, and kennel floors, but on an exterior surface they pose more risks and challenges than benefits. If you want a gloss or color on an exterior surface, an acrylic is usually the best or most common route.