The first is a Chessie WM covered hopper that is about
as dirty as they come. Most of this load looks like it missed getting
into the car. The second pic is of an old WM box car. Notice,
especially on the right side of the car that the white under the word "Maryland"
is streaking down the car. This is most commonly seen on white writing
on dark colored cars, like this one.
To streak a car you can use either of three methods: dry brushing, weathering chalks/pastels, wash. We covered how to do drybrushing before, but if you leave just a little more paint on the brush it will streak the car and not just high light the raised detail. If you have tried to dry brush you surely have done this by accident already. Weathering by chalks or pastels is also effective. That is what I did for the white spills on the covered hopper below. Finally the wash was used too on the same covered hopper. Here it was given added contrast by using an eraser in the middle of the panels to accent the dirt in the crevices. The Erie boxcar shows how white letters steak after years in the sun.