Normal optical glass passes very little UV light, special quartz based optics are used for lenses designed for specialist UV photography, most companies made a few lenses for medical, forensic and scientific applications.
OK. I think that destroys that idea. I wanted to print negs to cyanotype paper... I thought that this was the case and before I went crazy thought I would ask the gods of photography. ;-)
This has been discussed at length over on the Azo forum. A UV light source exists to enlarge on Azo paper. Late model Nikkor lenses are recommended because they pass much more UV light than Schneider or Rodenstock lenses.
If you don't own a Nikon enlarging lens, see if you can borrow one to try with the cyanotype paper.