OfficeSupplies101 has many different kinds of glue and adhesive. Glue Guns work as an easy application of hot melt glue (or hot glue). The gun uses a continuous-duty heating element to melt the plastic glue, which may be pushed through the gun by a trigger mechanism, or directly by the user. The glue squeezed out of the heated nozzle is initially hot enough to burn skin. The glue is tacky when hot, and hardens in anywhere from a few seconds to one minute.