Weathered freaight cars

I started weathering a few freight cars this week. I finally bought an airbrush its a passache VLS double action brush. I like the double action brush because i think you have more control then you would over a single action brush. I think the Rock Island car looks the best. To do these all i did was verly lightly spray the cat starting from the trucks moving slowly up with dirt. Then i sprayed the trucks and couplers with rust. In the future i want use some of my grimy black. I thought the process was going to be alot harder then it is. It takes me about 10 minutes to do a car. Heres some pictures of my first few cars. I plan to do more soon so i will keep you posted when i do some more cars.