Using the same Harbor Freight Red powder, each time I powder coat a new batch via tumbling with Black and White Air Soft BB's the coating seams to be getting darker. I am using the same temperature (400 F.) and time (20 minutes). I noticed that even when the powder coat just begins to melt, (so it is not too hot of a temperature causing the problem), they are obviously darker than the ones I produced previously. The attached picture does not show the true shades of Red, but when looked at with the naked eye, the ones I am doing now are quite a bit darker. Anyone else noticed this or know what is going on?