Walk the line

I was trying to find a procedural way of adding some shading and bleeding to my animation line, to give the impression of ink that has sat on the paper for ages. Even though, at the time of the film, the maps would have been brand new. I guess it's for the same reason that all medieval films have castles in them that look ancient and ruined, though they would have been new back then. Here are some mockups illustrating the various stages to make fill, line and shadow-matte into the final image...