I'm using Formulary BW-65 developer with Fuji MI-DUP film. So far, I've only done some cyanotypes, but the exposures have been close to what I get with normal negatives. I make test strips and dodge/burn on some negs, since it handles like paper. If you're negs are too dense, you may be under exposing--the film requires a lot of exposure compared to paper or conventional film. You may also be overdeveloping.
Originally Posted by Robert Ley