plating, anodizing, & finishing Q&As since 1989
Prepping and painting hot zinc die castings
We are trying to speed up our production process by trying to prep and paint zinc die cast parts as soon as possible after casting. We would like to do it hot and let the parts cool on their way to the next process...instead of cooling, then painting. This would greatly speed up our process. The parts are close to 750 degrees F.Dave Shepherd
- Ronan, Montana
If heat is used to crosslink the paint, this would be like making corn bread.
When you pour the batter into a hot pan you get instant curing at the hot surface, the substrate cools down, and you still have more to cure in the rest of the batter. It works fine for cornbread, but cornbread batter doesn't have a low flashpoint, you want two separate cures, and you can swirl the batter to get an even thickness in the pan. Powder paint would semicure upon contact with the hot surface, so there are problems to be overcome there, as well.
Falls Township, Pennsylvania
The 750F part is a little scary, but I think a possible solution might be implicit in Tom's answer. He's right that you can't use a coating that crosslinks by heat, but it may be possible to apply a thermoplastic coating instead of a thermosetting one. We have had good success applying protective lacquer coating (wet) to hot substrates, but never 750F, more like 200 F. It makes it easy to get nice film builds, but cosmetics suffer.
I believe that it is also possible to apply some powders to hot substrates.Michel Moninger
- Sarasota, Florida
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