Pinholes come from gas escaping during cure, from outgassing substrates, moisture in the powder or on the part, HAA systems at high build, or air trapped in heavy films. They let corrosion reach the metal and are unacceptable on outdoor or immersion work. Many show only under magnification or with a holiday detector, and they cluster on castings, welds and edges.
Got pinholes all along the weld seams, either moisture in the seams or the weld's porous.
Also heard as
- pinholing
- pin holes
Related terms
Outgassing
Gas escaping from a porous substrate during cure and blowing pinholes, bubbles or craters through the film.
HAA
Hydroxyalkylamide, the TGIC-free crosslinker used to cure carboxyl polyester powders.
Holiday
A skip, void or pinhole in the coating where bare metal is exposed.
Crater
A round dimple in the cured film where something with low surface tension pushed the melted powder away.