I used the mud color, just like my infantry. Okay, so the first step, is of course, to make sure your model is ready to VARNISH. Yep, that is right. In order to get the weathering powders to stick, you have to matte varnish the model first. I run Vallejo Color Satin Varnish Premium RC Colors through my airbrush. I ran this through and then cleaned out the airbrush thoroughly.
Once the model is dry, grab your supplies. The Weathering Master kit comes with an applicator that is the same as used for eye shadow. I destroyed this weathering up infantry. So I went to Wal-Mart and grabbed up some makeup wedges. Cheap and will work for what I need them for. You will also need some rubbing alcohol as a set agent, and then grab up a CLEAN large or medium drybrush.
Take the wedge and load it up with powder. Remember the adage less is more. And remember how the tracks move, as you will want to weather that heavier than other areas. I focused on the tracks first, and the armor plates around the tracks.
I then applied a light dusting of powder all of the top of the tank. All of the bottom parts, like going under the front hull, up the rear under the engines, I went heavy on the powder.
Once the majority of the powder is applied in the heavy areas, I worked it into the smaller cracks using the drybrush. I repeated this a couple of time, all over, until I was happy with the coverage.
I loaded the airbrush up with alcohol, turned the air down to 10psi, and shot the whole tank with alcohol. After this was dry, I applied the matte varnish over the model again.
The matte varnish reduces the impact of the powder, so if you want it to retain that heavy dirty look, or apply really heavy powder, apply the alcohol right after applying it, using an eye dropper. This works great if you are applying powder mud effects. Once that fully dries, then you can matte varnish again.
Okay, go out and make some dirty models!