Hi James,
The best what you can do : use powder as a base layer. Paint the head, bake it, use the airbrush to add details. Buy Devcon 30 minut epoxy - clear coat the spinnerbait heads or jigs. Done.
oh and iv noticed alot of air bubbles in my lead heads on my spinnerbaits
It seems, you lead is too hard. You need to mix it with soft lead and it'll be fine.