Hydroxyalkylamide crosslinkers react with carboxyl polyesters by condensation, giving off a little water as the film cures. That makes HAA systems prone to pinholes and gassing once film build passes about 3 to 4 mils, and they tolerate overbake less well than TGIC. In return they avoid the TGIC hazard label, which is why they dominate in Europe and are common on retail goods everywhere.
We switched to the HAA white and now every part over four mils has pinholes along the edges.
Also heard as
- TGIC-free polyester
- Primid polyester
- beta-hydroxyalkylamide
Do not mix it up with
- TGIC: TGIC cures by addition without releasing water, so it builds thicker films with less gassing.
Related terms
TGIC
Triglycidyl isocyanurate, the classic crosslinker that cures carboxyl polyesters into weather-resistant films.
Polyester powder
Powder based on polyester resin, the standard choice for outdoor parts because it holds color and gloss in sunlight.
Pinhole
A tiny hole running through the cured film, often down to bare metal.
Film build
The thickness of the cured coating, usually given in mils or microns.