Which adhesive is usually supplied in two parts which must be mixed prior to use

An Epoxy or epoxies

An epoxy is composed of two parts, a resin and a hardener. After proper mixing the epoxy begins the curing process. The benefit is the versatility of these blends to be tailored for specific applications. Depending on the situation the chemical reaction that occurs, once started does not finish until the curing process is finished, meaning that special situations like extreme heat, or underwater, once the epoxy process is started it will finish, regardless of most other most chemicals or factors in the surrounding environment.