weathering with chalk pastels

When using pastels experimentation is the key.

For exhaust staining I use a combination of black and white (I've never seen a grey pastel) and apply them alternately to get a better 'contrast'.

For a dusty effect mixing white and various earth tones do the trick. To simulate mud I mix pastels with gloss clear, then blend it all together with dry pastels for a more realsitic effect.

I have never taken the base colour into consideration when using pastels as I use them for weathering only.

If you wanted to simulate sun bleched paint on an a/c or armour model, it would be best to lighten the colours you spray on the model gradually to reach the effect you want.

AndrewT wrote:

First of all chalk pastels should not be wax based? When weathering ,If the base colour is green,what should the colour of the chalk pastel be,dark green or black?

Generally, you will find two types of pastels "soft" (ie "chalk" based) or "oil" pastels. You want the "soft" type - DO NOT use oil pastels.

It really depends what type of effect you want to achieve. For example, exhaust/gun streaking may be black, dust/dirt may be any number of earth/brown tones.