Nicely done! The sepia tone is really nice. Are you painting with dyes?
This was actually done on copy paper with black ink and aquamarine water color. I Photoshopped it, changing the hue first, and then adding a layer of scanned newsprint set to 80% "pin light" which replaced the blacks with that consistent rust-colored line. I think dyes would be the only way to get that rusty line to begin with, don't you?