I've had Testor's metallic paints have different results. I think it can tend to have weird not-drying effects if it's not mixed up so well. Any time I'm using a metallic spray paint, I shake it up for a full minute... yes, it seems like a really long time. During that minute, I'll run warm tap water over the can periodically and shake it more. Do this three or four times to make sure the whole volume of paint in the can is a consistent warm temperature. The warmth helps it flow well. The shaking helps it mix well. Metallic paints tend to separate much more than regular colors and that can really muck up your final results. Also the kind of plastic you're spraying on can effect the results, but you're good with the styrene these models are made of.