We have a powder coating system that coats perfume bottles. We are using powders from a French supplier. We are facing a problem of the powder chipping off with the slightest pressure. What could be the problem? M.M.
Normally, powder coating glass is preceded by the application of a primer or adhesion promoter. You didn’t mention if you use one of these systems. Adhesion promoters like silane have been used in glass coating for years. Primers (usually liquid) are also recommended by your powder supplier and must be compatible with your powder topcoat.
If you use one of these systems and you still have chipping problems, look to your cure system as the source. Under- or over-cured powder coatings will chip with little effort. Proper film thickness is also important to prevent chipping, as thicker powder coats tend to be more brittle.