Acrylic sealant is a synthetic protective material used in a wide range of applications. It seals all types of materials to make them gap-free as well as resistant to infiltration from foreign matter. Variations of acrylic sealant are used extensively in the construction industry on residential and commercial properties.

Sealing is called caulking; the joints in buildings require a caulked closure to seal gaps and keep each joint waterproof. Closing construction joints with sealant is also done to keep dirt and insects out. Since building joints need to be allowed to have some movement, a flexible sealant must be used. Flexible acrylic sealant has a rubber-like quality to it when it dries; it's often the preferred choice to seal building joints. Drying in reference to caulking is called curing.

The drying or curing time for acrylic sealant varies according to the humidity and temperature of the location. When fully cured, flexible sealant then forms an elastic, rubbery coating over building surfaces and gaps. In addition to building joints, rubber-like sealant is used around windows and doors as well as to seal foundation cracks. Gaps in building siding can also be sealed with acrylic flexible sealants. Mold-resistant acrylic sealants are favored for use in wood construction applications where mold could become a problem.

Silicone is often added to acrylic sealants. Silicone is an element that is non-metallic; it adds a flexibility to acrylic sealant that it doesn't have on its own. Siliconized acrylic sealants are not only less likely to crack, they also tend to dry, or cure, faster. Many silicone-based acrylic types of sealants can be painted after 24 hours of curing or drying.

Clear, white, black, brown, gray and tan are the typical color choices available in acrylic sealants. It's common for sealants to indicate on their labels the number of years they're expected to last. For example, an acrylic sealant designed to last 20 years would feature the number 20 on its packaging. The number is still only a prediction because the weather and application conditions affect the durability of sealants. At some point, a sealant likely will crack and need replacing.

Acrylic sealants can be used on plastics, wood, concrete and metal — both indoors and outdoors. Driveway contractors use acrylic sealant on brick paving. The sealant must be applied after the paving is cleaned with a power washer, because otherwise dirt and debris will be sealed in. Acrylic surface sealants are also used to seal airport runways to make them chemical- and weather-resistant.

In smaller applications, acrylic sealants are applied with a caulking gun applicator. There are different types of these applicators, but a common caulking gun looks like a large cake frosting decorator because of its cylindrical shape and narrow tip. The caulking gun is also used in a similar way, as the hollow cylinder is filled with caulk or sealant and applied to surfaces from the tip or end.