Here at George Eastman House we've been holding workshops on how to make photosensitive materials for a variety of contact printing processes. Many of these have been matched with period camera negative processes...but we also use film and digital negatives as an alternative.

These printing processes range from photogenic drawing [Talbot, halide fixed] to salt print, chromotype [Hunt's direct positive], Bayard's direct positive process, albumen on paper and glass, collodion transparencies on glass, collodion on paper [gold and platinum toned] and various gelatin emulsions [gaslighjt and silver bromide].

Often it's a question of the particular type of negative that fits the printing medium. Paper negatives for example have a lot of noise, where glass negative don't.