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OUTGASSING BUBBLES FROM CAST IN PAINT

WE ARE A POWDERCOATING SHOP LOOKING FOR A LIQUID PRODUCT TO GO OVER CAST TO STOP VAPOR OUTGASSING BUBBLES FROM THE CAST IN THE PAINT.

WYATT BUCHANAN
- BINGHAMTON New York
2000

My experience with solving out gassing problems with powder coating is to heat the part to 250 F for 20 minutes to drive the internal gas out, before coating. I am guessing that your system as configured doesn't have heated section specifically for out gassing prior to coating. If the dry off is the only equipment you have to do this, elevate the temperature in that section, and see if you get better results. I am not aware of a liquid coating that will withstand the pressure of the internal gasses to prevent the rupturing or "popping" of the powder coating. There are fillers to smooth the rough surface of castings that will be a good substrate for the powder coating, but I would be skeptical about them holding the gasses in during curing. You might try something like that, but I have my doubts. Let me know if you find something that works.

Randal Rockwell
- Mishawaka, Indiana
2000

To degas castings will require a heating schedule GREATER that the powder cure cycle. If that is not viable try a dry-in-place chrome-resin pretreat. I believe Brugal 5TF from Procoat may be available in the states. An alternative would be to dip in PVB based blast primer which will penetrate the surface being based on alcohol/MEK. All solvent must be driven off by force drying to prevent solvent bubbling.

Roger Bridger
- Croydon Surrey UK
2000

We have found that the best way to solve the problem of out gassing is to buy a product specifically designed to do just that. This special type of powder stays in the gel state longer, and allows all of the air to escape before it completely cures. The cure times are not much longer either. DuPont has one that works great for us. It is called AGP Black.

Hope Tyburk
- Canton, Ohio
2000