Sealers are effective, but not infallible. They are designed to minimize stains, but not to entirely prevent them. The purpose of sealers is to prevent as many staining agents as possible from penetrating the pores of the stone or terrazzo. If the stain does not remain at or near the surface of the stone, it will be much more difficult to remove. Remember, once sealers are applied, they will usually need to be maintained. Depending on the sealer, some will need to be stripped or re-applied more regularly than others.
Sealers, similar to cleaners, should be pH balanced or neutral. Some sealers may be approved for ceramic or wood, but this does not mean that they are safe for natural stone. If the sealer is acidic, damage to the stone’s surface will result. Chemicals high in acid will break down the mineral calcium carbonate, which is the building block of marble.
Sealers are offered with a water or solvent “base”. The sealer base ads as a carrier for the chemicals that actually seal the stone such as urethane, silicone or acrylic. Water based sealers are “user-friendly” and typically easier to use than solvent based sealers. Solvent based sealers are usually longer-lasting, but most need to be applied by a qualified contractor.
Consult a professional for the appropriate sealer specific to your needs.