Hi. Just new to this site, but thought I would tell you what I use. No airbrush, simply Artist Acrylic paint. Because it's water based, you can get some great worn, weathered effects, by using warm water, once the paint has dried, which doesn't take long at all. With a bit of practise, all sorts of weathering can be achieved. Hopefully, when I get the hang of posting photos, you can see what results can be achieved using this method.