Stone sealers are necessary sometimes. This is the most definitive statement I can make about them. And the most important for the stone owner to remember.
Consider the following:
Some stone surfaces need no sealer. Using sealer actually will leave a residue that can’t be removed with out a fairly expensive procedure.
Sealers exist to provide a level of water and oil repellence. This is all they do. They don’t keep the surface clean or shiny.
The finish of the stone — hone or polish — will in some cases determine the necessity of a sealer.
Sealers are delivered in either a solvent or a water base.
Sealers are resins disbursed in water or solvent.
An enhance, that brings out the color in a stone, is a sealer.
Application methods of the sealer is as important as the sealer itself.
Occasionally installers will attempt to cover defects with a sealer.
On marble or calcite based stone, no sealer will prevent low pH etching from household acids like vinegar or lime juice.
A crystalizer process that uses steel wool and a carnuba wax combined with an acid is not a sealer and will damage the stone.
If you ask a typical stone retailer the answer about sealer is that all stone must be sealed. They sell sealer.
Sealers will not dry uniformly, and as the sealer dries, the part that dries first will seal the stone and the undried sealer residue will lie on top of the stone.
You should never be able to see a sealer on top of the stone. If you can, and it is a glossy “topical” sealer, you have damaged the stone and will need to use an expensive procedure to remove it.
Acrylic, urethane, waxes and concrete products are unsuitable for stone.