Hot melt ahesive (or hot glue) is a form of thermoplastic adhesive that is commonly supplied in solid sticks designed to be melted in a special gun. The glue comes in cylinders of various lengths, and is pushed into an electric hot glue gun. The gun contains a heating element to melt the plastic glue, which operates all the time the gun is plugged in. Squeezing the trigger pushes the stick through the heating element, ejecting molten glue which is initially hot enough to burn and blister skin. The glue is tacky when hot, but hardens and stops being sticky in a few seconds—a minute at most.