Review: Hot glue

This is part of a series in which I review various glues etc. (Epoxy, Superglue). Today we’re looking at an arts and crafts favorite: Hot glue.

Hot glue is surprisingly useful for quickly building large, temporary, non-precise structures and tacking things in place.

Basic properties:

  • It can be useful to think of hot glue as an adhesive filler, rather than as a glue. This stuff is good to keep things roughly in one place, and fill gaps. I use this a lot to keep wires/switches in place inside enclosures, for example. For anything beyond that, other glues (usually epoxy) are better suited.
  • Bonds to a lot of materials, like plastics or wood, but bond depends on temperature. Usually performs quite poorly on metals.
  • Can fill gaps, and can be built up into layers pretty quickly. Can for instance be used to make nice fillets in glued plastic cases. Keep in mind though that ethanol will break the adhesion on hot glue eventually, so this is not the best choice for boxes that need to be cleaned often. It is also practically impossible to make thin layers of this stuff because it hardens as soon as it thins out between two surfaces.
  • Remains flexible/rubbery – look at the un-melted glue sticks, that’s exactly what the glue joint ends up as. This makes hot glue pretty much completely unsuited for any joints that require stiffness.
  • Best use cases are making temporary enclosures out of plastic or wood, or tacking things in place, like for instance wires, switches, etc.

Pro tips:

  • You will eventually burn yourself on this stuff.
  • Forms thin strands, so don’t use in locations where you don’t want strands of this stuff floating around.
  • A can of keyboard cleaner (whatever refrigerant they use these days) held upside down can be used to quickly cool the surface of a glob of hot glue and set it quickly. This will however deposit a lot of the bitter additives they put into the refrigerant, and this stuff is not great in terms of literally dispersing greenhouse gas.
  • To remove hot glue, ethanol/acetone can be used.
  • To make pretty well performing hacky brackets or mounts in a pinch you can attach a piece of equipment with hot glue, build up a well shaped support structure (possibly shaping it with a razorblade), and then cover it with epoxy to form a better structural layer. If done well, this approach can be used to very quickly make mechanically decent structures for quick rigs at summer schools etc.
  • With some practice, a covering of hot glue on a cable can make odd looking but decent strain relief.
  • If you need maximum adhesion, it’s worth it getting good quality glue sticks, so consider not just getting whatever is cheapest. Steinel has been recommended, but there is a whole world of options out there.

How to use:

  • Give enough time to pre-heat the gun. barely melted hot glue does not adhere well.
  • As always, consider cleaning the surfaces if you need maximal adhesion.
  • Apply the glue.
  • Do not touch until you are sure the glue has cooled, unless you like dragging thin strands of the stuff across the lab.

What to buy:

  • Get a decent hot glue gun that heats up quickly, the whole point of this stuff is speed.
  • Avoid small glue guns, a main application area for hot glue is large glue joints.

Rating: ⭐⭐⭐⬜⬜


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