I repaint quite a few broadheads.I've had real good luck with Krylon Camo paint,as well as Hunter Specialties camo,green,tan,black etc..It is flat but fairly smooth and seems durable if you let it cure.
As far as logwood dye,I've boiled traps in it for 50 years and actually have two pots going right now.It wouldn't be my choice for broadheads.Paint them,it will protect your investment.I would rub them down with Scotchbrite and make sure they are clean and free from dust.Let them cure till they are close to odor free before shooting them.