[Zeke]

You can't sand metallic. You're better off using a 2 stage system or spraying some clear over the paint.

One trick I have used over the years is to blend acrylic metalics and clear, since clear is the base anyway. Here's how you do it: Most acrylics take about six coats or three double wet coats. Start out with straight silver and do your first two coats. Then, 30 min later, 2 more. Then add some clear; a little less to the first of the next 2 coats and a little more to the 2nd. Then, proceed to a nice full clear coat, full enough that you won't sand through it. If you do, you won't go directly into the pure silver paint.

If you sand pure metallic, you expose the metallic particles to the surface and you can see that. They may even oxidize.

If you "blueprint" a HF gun, it will paint OK. Look at a Binks or a Devilbiss and see the difference. All of the holes have to be very good with no burrs or abberations for a good, even spray pattern. That is very important with metallics.