FLAKING PAINT
After getting the base paint just right and the basic weathering, a typical worn look can be made by simulating paint chips flaking off. Getting the paint to look as if it is flaking off is not easy. Some use a silver undercoat and then sand off the paint over it to produce a worn look. To me, however, aircraft paint doesn’t flake off smoothly unless there’s a consistent wearing agent such as feet on walkways and arms resting on window rails. I think to get the most realistic paint flakes, you have to paint them on.
I use two techniques. The first works well for small chips in the paint, and it produces a random effect. Dip plain-old steel wool (I use a coarse grade) in a little puddle of steel-colored paint (not silver!). Silver is too bright; you want the chippedoff area to look as if it has been there a while. Steel paint looks more like oxidized aluminum and appears more natural. After dipping the steel wool in the paint, pat it on a piece of cardboard or cloth to remove the excess. Then pat the steel wool on the surface you want to look like chipped paint. Vary your angle, and rotate the steel wool to keep it random.
The second technique is a little more time-consuming and more tedious. I use a “liner” brush along with some steel enamel model paint and just paint the chips on. The fine liner brush adds to the linear effect, which looks scribbled along the leading edges of control and flight surfaces. Again, apply the paint in a random pattern, but keep in mind the effect that may be happening on the aircraft. On the leading edges of the cowl and wings, the paint will chip more with the airflow due to rocks, grit, bugs, and so on that knock the paint loose. On fuselage side panels, the paint chips on edges and runs along the panel seams. Hatches get more wear, so around those edges the paint flakes, and sometimes the panels get thrown on the ground and get scratched.
Paint peels away from rivet heads as well, so to get that effect, you have to paint steel around rivets, too. Keep all this in mind, and apply your paint with a purpose, but also keep it random. When in doubt, check your reference.
On the leading edges of the cowl and wings, the paint will chip more with the airflow due to rocks, grit, bugs, and so on that knock the paint loose.