Topical sealers (stone coatings) generally are water based acrylic or oil based polyurethane. Like wood varnish, they form a coating over the surface and tend to be cheaper than penetrating sealers but have disadvantages. Topical sealers are like a film over a floor. It looks great for a while.
Topical sealers (satin, semi-gloss and high gloss or wet look) are likely to noticeably change the appearance and slip resistance of the surface, lock in moisture and wear relatively quickly as they collect abrasive materials in the soft coating. When they wear through, the entire surface has to be stripped and resealed.
Color Enhancing Sealers
Color enhancing sealers were designed to highlight the natural stone color look as when wet or moist. Color enhancing sealers may add various levels of shine to the surface of the stone.
Penetrating sealers are generally longer lasting than topical sealers, but vary in performance. Many penetrating sealers use fluorocarbons (e.g. Teflon) or silicone, can work well and are somewhat breathable. Penetrating sealers still have a limited lifespan in comparison with the surfaces they are meant to protect.
Impregnating sealers are generally the longest lasting, fully breathable and allow water vapor to escape and provide the best protection without substantially altering the natural look or slip resistance of the surface. There is a permanent invisible sealer 'Drytreat Stainproof' with a 15+ yr. warranty if applied by an 'Drytreat' accredited applicator and your stone never has to be sealed again.