Yeah regarding metallic colors from Vallejo, I don't use them with the wet palette as much as I used to. I found that while they worked OK on the palette, left on long enough, the pigments separated from the color and really didn't mix back into a solution again. I have had a little success wicking the excess moisture out of the paint on the palette, but even better is to use a hard palette-whether ceramic, or even those fake credit cards that come in junk mail, and just put a little blob of the color down. Right from the bottle. I may add a tiny bit of water, or wet the brush. But it's thicker than the paint on my palette, and applies better. Silver, gold, and gunmetal are the only Vallejo colors that behave that way for me. I find that a little thicker, they just work better for me.
Prost!
Brad