I'm almost complet with my M2A2 Bradley in OIF dress.
I wanted to ask if anyone has grinded Pastels or Chalks to a powder and then mixed the "dust" with a liquid to spray with, like water, alcohol, mineral spirits?
I'm after the "misting" effect of dust on an AFV and thought that a "cocktail" of this blend would be easy to use instead of paint.....

I have never done this but I feel the method you discribe is not the way to go as I can see no advantages in it at all.

In General:
I have done this basic technique and find it useful for spot washing. I would NOT run this through an airbrush, I don't trust myself to get the powder fine enough.

The advantage is that I can match my pastel weathering spot on and I have a huge array of pastels that I can match just about any color.

If you want a light dusting on your AFV go with Tamiya's buff over a wash/pastel base of the basic color that you are looking for in General

Plus with OIF dust is it - I believe that a thin version of Tamiya Buff with a small mix of white would give you the very light dust to use.

I've done it.. works fine.. used Tamiya Thinner.. did it with both Grinded Pastels and also tried MMP powders...

Still do some hand brushed dusting work too

I think this would only create a clogged, hard to clean airbrush, with nothing on the model!