I'm having a problem with small(1/48 and 1/32oz) horseheads. I use a heat gun when dipping the head in the powder paint, then use a small front load toaster to cure. After curing I notice my chartreuse heads have a brownish tint to them, but not prior to curing. The oven I'm using is a cheap one from Wal-Mart, it does have a thermostat on it. I do as the directions say 350 degrees to 20 minutes. Any suggestions to stop the "browning" of the finish?