I am looking for some advice to further weather the rail station roof shingles. So far I have painted medium primer gray, followed by buffing with a dremel and abrasive pad, followed by individual painting of random single shingles, with some soot runs around or from eyebrow windows , chimney etc. I was considering buffing with a dremel with a light abrasive pad again and light india ink wash.

This is a first attempt at uploading a picture so hopefully it looks ok. You thoughts / input?