Hi, juniormodeler!
That was all just done with the ol' airbrush, using gradually lighter shades of Tamiya acrylic Dark Earth and Buff.
This is the first model that I didn't do much drybrushing on. I've been reading a lot lately about the logic and physics of weathering, and decided to give the "no-(well, little!) drybrush" technique a try. Since I wanted to depict a relatively clean vehicle, I thought this technique suited the subject.
I used the airbrush much more than the drybrush on this model. Rain streaks, soot, dried mud, dust, all ABed on.
And the toothbrush! I love that technique! I wanted to get a look of a dry, dusty vehicle that may have been through a puddle or two in the last coupla hours, so I loaded a toothbrush with what was basically a dark brown wash, and just lightly flicked it about the front and rear fenders and other places I reckoned a drop or two would reach.
Looking at the pix, I should have gone a little heavier on the toothbrush splashes. I can barely see them!
I find the look quite convincng, though.