Sealant is a substance used to block the passage of fluids through the surface or joints or openings in materials, a type of mechanical seal. In building construction sealant is sometimes synonymous with caulking and also serve the purposes of blocking dust, sound and heat transmission. Sealants may be weak or strong, flexible or rigid, permanent or temporary. Sealants are not adhesives but some have adhesive qualities and are called adhesive-sealants or structural sealants. Sealants generally contain inert filler material and are usually formulated with an elastomer to give the required flexibility and elongation. They usually have a paste consistency to allow filling of gaps between substrates. Low shrinkage after application is often required.
Sealer is a protective coating or treatment which prevents or retards foreign liquid or matter from penetrating the stone by closing the pores in the surface. Stone sealing is the application of a surface treatment to products constructed of natural stone to retard staining and corrosion. Should natural stone counters be sealed? In many cases it makes sense to seal your stone with a quality sealer. Once properly sealed, the stone will be more resistant against everyday dirt and spills. Generally, you should seal most countertops annually. Of course, porosity of the stone and sealer quality can vary, but several natural stone sealers last 3-5 years and some are rated for 10-15 years if the stone is diligently and properly cared for.