Hot melt, hot glue

Hot melt is a solid thermoplastic adhesive that is heated until it flows, then gains handling strength as it cools. There is no solvent to evaporate and no normal chemical cure. This makes it fast. It also means the bond can soften again when hot and become brittle when cold. Sticks sold for craft guns, packaging, woodworking and industrial polyolefin bonding use different polymers and operating temperatures. Treat hot melt as a family, not one material. Apply it to a surface that can tolerate the gun temperature, then bring the parts together immediately. Open time is often measured in seconds. A large bead stays workable longer but also holds more heat and can distort foam, thin plastic or fabric. Hot melt is good for positioning, light assemblies, packaging, cable restraint, craft work and filling irregular spaces that are not heavily loaded. It is poor where a joint sees sustained peel, high temperature, direct sun behind dark material or a long-term structural load. Many grades creep under steady stress. A thick bead may look strong while touching only the high points of a dusty surface. Industrial grades can bond difficult plastics, but that does not mean a clear craft stick will do the same job.

Rapid craft and model assembly; packaging and carton closing; temporary fixtures and positioning; cable and component restraint; attaching trim, foam or fabric where the substrate tolerates heat; low-load gap bridging.

Remove dust, oil and loose fibres. Preheat heavy metal if the maker recommends it because a cold heat sink can freeze the bead before wetting occurs. Use the correct stick diameter, chemistry and gun temperature. Apply an even bead, join immediately and hold still until cool. Test heat-sensitive foam, coatings and fabric on scrap.