For mallard heads, I use Testors products. After a good scrub, rinse, and dry, I start by taping off the bill so it doesn't get sprayed. I use spray Chezoom Teal metallic first. After it has a good few thin coats, I switch to a forest green metallic and give a VERY LIGHT coat along the top and cheek patches. After that has dried and you're happy with the coverage, a few light coats of flat or matte spray paint knocks the shine off. Untape the bill and use Zinc Chromate and brush it on. It dries flat. Use gloss black for the tip of the bill and the eyes and then flat black for the nostril holes.