Weathering Tank Treads With Pigments
The technique worked great. I ran into a bit of trouble because I don't have the clay brown pigment. Thought I did, but I couldn't find it. I tried using a similarly colored Vallejo pigment, but it didn't go on as nicely as the Secret Weapon pigments. I also experimented with a weathering stick, which is a thick paste, a little softer than a grease pencil. It was about as effective as the pigments except it tended to stick on thicker. Anyway, I got results I was happy with in the end.
Tomorrow, I will spray these and the tank itself with top coat. Then I'll glue the treads on the tank, and it'll be done. These powders are just brushed on; they aren't really stuck to the surface very well. So, it has to be sealed, or the powder will rub off everywhere.
To deal with the mess, I worked in a cardboard box, like the top of a printer paper box. It worked out well. I managed to avoid spilling powder everywhere, even though I tried really hard a couple times.
Also note: use a mask when working with pigments.