Pastels

There was a time I used Humbrol enamels for everything, including any weathering I was doing. I now tend to use artist's oil pastels for almost all weathering on aircraft, and a good deal on AFVs. I'm not talking about the waxy crayon type pastels here, but the crumbly square ones about 6cm long. If you run the edge of a scalpel blade across the tip at 90 degrees to the pastel, you can scrape off a fine powder that you can subsequently pick up with a fine stiff brush and stipple or stroke onto the surface of your painted work. They are absolutely magic for exhaust staining (both ejector exhausts themselves and their output), gun port exhausts, rust, dirt etc. Wetted slightly they can be painted on to emulate oil and other fluid staining. I have about ten individual colours which serve for almost everything, but the two most used are black and a dark brown (possibly burnt sienna, I can't quite remember), which get 95% of the work done--I don't know how I used to live without them.

Spraying

Sometimes exhaust staining is best done with the trusty airbrush, mostly on large aircraft such as the Dornier Do-217K-1 in the gallery, or smaller aircraft in larger scales. In this case, spraying exhaust staining is a quicker and more effective method, achieved by spraying lighter greys over a brown/black base.

The other scenario where spraying might be used for weathering is when an aircraft is heavily weathered (maybe in a desert environment) or badly damaged (perhaps in a diorama of a crash scene). Overall "misting" of the model or selective spraying with an appropriate colour then becomes the method of choice.

Paint chipping

As aircraft are usually made from metal or wood/fabric combinations and then painted, when exposed to operational wear and tear this paint will become worn and chipped. Areas that are particularly affected by this type of "weathering" are those that receive the most operational abuse--areas where the crew ingress/egress the aircraft, removable panels, cowlings, ammunition bays, propellers, leading edges and so on.

Wherever this occurs on the real thing, it should be represented on the model by some method. I used to dry-brush areas with aluminium enamel, but I find this results in too much "stardust" effect rather than the impression of operational wear. I've also used a silver marking pen, and while initially impressed with the results, there is not enough control over the areas formed, which tend to be much larger than is realistic. Going back to the aluminium enamel, applied with the tip and edge of a sharpened cocktail stick, got a much better result--although it is a long and tedious process. I've tried using S'n'J spray metal powder with some success, and though much too bright it does tone down much more effectively with pastels than the silver pen, which seems immune to such attention. The other prospect which I had an abortive fling with on the PBY B-25 Mitchell is to spray the model silver before applying the main camouflage, and then actually "chip" the paint off--another thankless prospect. I do have another couple of ideas, which I'm going to try out soon, and I'll let you now how they work out...