How to Drybrush:
Dry brushing is exactly what it sounds like, brushing a model with a "dry" brush. The key is to get just the right amount of paint on the brush so it is practically "dry". I like to use a paper towel to wipe off the extra paint. When I see that I am just putting paint on the raised detail of the paper towel, I know the brush is ready to apply paint to the model. Below are some examples of dry brushed models.
This is a hopper that has had the wheel sets drybrushed
with a light grey. Notice how nice the detail stands out now.
Below is a B&O box car that I applied an overspray of rust in
part of the roof and then dry brushed some light grey on top of it.
This really brings out the detail of the roof. Also the sides received
a light dry brushing. Notice the top of the door is highlighted by
Below are two pics, slightly out of focus. I just wanted to
show how you drybrush on a paper towel until you are just coloring the
raised detail. Also an example of two roofwalks, the front one has
not been drybrushed, the back one has.