A better and more authentic effect could be done if you take your time and by adding different shades of pigment to represent fresh and dry mud, dust and rust. But I am thinking 'war game' model and I think this quick application gets a nice effect for little effort...
|Mmmmm...Nice and 'clumpy'|
Applying the powder is very simple - I made a thin mix of PVA glue and water and brushed this onto the surfaces I wanted the mud to stick. I then sprinkled and dabbed on the pigment to get a mixture of dusty and clumpy mud effects. A final coat of matt varnish will 'fix' the effect.
I now know what to expect when using this medium and would be tempted to be a bit more adventurous - and careful - on a display model I have in mind. By layering the effects - using a variety of effects mediums - you could produce a very realistic mud effect indeed.
One thing I would say though, Vallejo pigments are comparatively expensive (I got mine in a sale otherwise I would balk at the price) and I think the cheap alternative of grinding up artist's conte crayons into powder would achieve just as good and effect at a fraction of the cost.