Gel time is usually measured on a hot plate at about 400 F by stroking melted powder until it strings and then stops flowing. Fast-gel powders, around 30 to 60 seconds, set quickly but give more orange peel; slow-gel powders, over 150 seconds, flow out smoother but can sag. Gel time is a quality check on incoming lots and a clue when flow or texture changes.
Lab says gel time on the new lot is 70 seconds, the old one was 110, that's your orange peel.
A change in gel time between lots of the same product is often the first explanation for a sudden change in smoothness.
Also heard as
- hot plate gel time
- stroke cure
Related terms
Flow
How far and how smoothly melted powder spreads out before it gels, which sets surface smoothness.
Orange peel
A dimpled surface texture like the skin of an orange, the most common appearance complaint on powder.
Cure schedule
The time at temperature a powder needs to cure fully, measured at the part's metal, not the oven air.
Crosslinker
The hardener in a thermoset powder that reacts with the resin to tie it into a network.