A powder built from a resin and a hardener that stay unreacted at room temperature and react once the film melts in the oven. The crosslinked network gives hardness, solvent resistance and heat resistance that a meltable plastic cannot match. Epoxies, polyesters, hybrids and urethanes are all thermosets, and together they make up the great majority of powder sprayed on conveyor lines.
It's a thermoset, so once it's through the oven there's no reflowing it. Bad parts go to strip.
Also heard as
- thermosetting powder
Do not mix it up with
- Thermoplastic powder: A thermoplastic only melts and freezes again; a thermoset reacts chemically and stays set.
Related terms
Thermoplastic powder
Coating powder that simply melts and solidifies on cooling, with no chemical cure, so it can be remelted.
Crosslinker
The hardener in a thermoset powder that reacts with the resin to tie it into a network.
Cure schedule
The time at temperature a powder needs to cure fully, measured at the part's metal, not the oven air.
Gel time
How many seconds a powder takes at a set temperature to go from melted to a rubbery gel that no longer flows.