Sealants are particularly effective in waterproofing processes by keeping moisture out (or in) the components in which they are used. They can provide thermal and acoustical insulation, and may serve as fire barriers. Sealants can also be used for simple smoothing or filling.

A sealant, once applied, is used to prevent the penetration of air, gas, noise, dust, fire, smoke, or liquid from one location through a barrier into another. Desirable properties of sealants include insolubility, corrosion resistance, and adhesion. Sealants can be categorized as bellow:

• Chemically reactive
• Physically reactive
• Non-reactive