Adhesive caulk is a material used primarily in the construction and home improvement industries to join and seal seams. It adheres firmly to the surfaces and fills in the gaps. Filling in cracks with this type of flexible sealing compound not only helps prevent water from seeping into cracks, but it also prevents dust, air, or insects from getting into those cracks. Typically, adhesive caulk consists of ready-mixed materials such as silicone, polyurethane, polysulfide silyl-terminated polyether or polyurethane, and acrylic sealants.

What makes adhesive caulk different from other types of caulk is its adhesive property. Most caulks have a fixed lifetime, after which they have to be re-applied or “recaulked.” Adhesive caulk, however, typically has a longer life than many other caulks because of the additional adhesive properties in the caulk. Still, depending on the particular application of adhesive caulk, recaulking may be required.

While caulking, one has to be very cautious about the amount of caulk applied. Too much or too little of the adhesive caulk can affect the look of, as well as the protection afforded by, the caulking. Proper application typically requires that the surfaces to receive the caulk be cleaned. Alcohol is often helpful in removing any grease that might prevent a tight bond with the caulk. Proper application also requires that the manufacturer's instructions on the caulk itself be followed.

Caulk is a moist substance with a similar consistency to peanut butter. It's typically applied with the use of a caulk gun and works via a chemical reaction that causes the material to harden when exposed to air. Before hardening however, the caulk seeps into the crevice and even the small pores of the material to which it is applied. After it has dried thoroughly, one may choose to paint it to make it blend in with the color of the surrounding material. Alternatively, one can buy tinted adhesive caulk.

For general household caulking needs, acrylic caulk or silicone caulk can also be used. Acrylic caulking is generally preferred for a neat caulking finish. On the other hand, silicone caulking is generally used for applications that require water-resistance. Silicone caulk is popular because of its fire-resistant, non-stick, and rubber-like properties. It also has low chemical reactivity and low toxicity.

Some of the other common types of caulk are sanded caulk, gutter caulk, and fire caulk. Sanded caulk is usually used with tiling and other flooring applications. Gutter caulk is used to prevent leakage in gutters, and fire caulk is used in containing the flames and heat in a furnace or fireplace.