Question: What is the difference between a sealer and a sealant?

Answer: Although these terms often are used interchangeably in everyday conversation, and sometimes in manufacturers' literature, they do not describe the same thing.

A sealer is a product that is applied to a surface, usually to reduce the penetration of some undesirable material, such as water or chlorides. Sealers may penetrate into the surface or form a thin surface layer, typically 3 mils or less. Thicker surface treatments are usually called coatings.

A sealant, on the other hand, is a thicker material typically used to fill a void, gap, crack, or joint. Sealants are offered in a wide array of formulations designed for specific applications or types of construction. They can be rigid or flexible, and self-leveling (for horizontal applications) or nonsagging (for vertical or overhead use). Some sealants feature a chemistry that makes them nonstaining. Manufacturers sometimes offer tinted sealant material, for use where appearance is a major concern.

There also is a seal, which refers to a gasket, strip, or gland. A seal usually is placed between panels or at an isolation or expansion joint. Most seals are prefabricated, but some are field-molded.

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