I can't be sure because we don't know the origin of your powder, but it sounds like maybe it was under-cured and didn't have enough time to flow out. Caswell powders have a cure rate of 400 degrees at 14-15 minutes. I have the same Harbor Freight powder gun, and have used Caswell powders from the beginning. I've had excellent results with smooth glossy finishes. Try curing a little longer and see if it helps. Use an oven thermometer from the local hardware store. If your part will cure near the oven floor, put the thermometer near the floor too. Practice on a few pieces of scrap metal so you don't have to repair any experiment gone bad.
Sandblasting is probably a quicker and easier way of prepping your parts. It also gives the powder a good surface to adhere to. It's possible that something in the laquer thinner could be contributing to the orange peel, but I still think it may just be under-cured.
Hemi-T
|