|Roof before pastel weathering|
|Roof after pastel weathering and rust|
However, remember, working in N Scale, people will not be seeing the work from too close up. Your work will need to be a little bolder, more exaggerated, to be seen, much like what is done for a theater production, I have often thought.
I'd encourage modelers to experiment with this technique and see what happens. I like the look, and will like it better when I get a better hand at this. Experiment until you're happy with the results. After all, it's your model and in this case it's my railroad. One interesting thing about this hobby is now when I'm out I'm making mental note of various architectural and town details that I see. That keeps things lively. Happy modeling.