Undercured powder often looks normal but has weak solvent resistance, low impact and adhesion, and soft surfaces that mark and stain. It fails the MEK rub test and cracks on reverse impact or bending. Common causes are heavy parts that never reach PMT, line speed too fast, a dropped burner or an oven cold zone. Putting undercured parts back in the oven usually completes the cure.
These rub off on the MEK rag after ten strokes, they're undercured, send them back through.
Undercured parts often pass visual inspection and the customer's first look, then fail when they meet solvents, cleaners or a hard knock.
Also heard as
- undercured
- underbake
Related terms
Overbake
Cure that went too hot or too long, causing yellowing, gloss loss and brittle film.
MEK rub test
A cure check that rubs the film with a cloth soaked in methyl ethyl ketone and rates how much softens or rubs off.
PMT
Part metal temperature, the temperature of the substrate itself, which is what actually drives the cure.
Fingernail test
The rough floor check of cure: dig a thumbnail into a cooled part and see if it marks.