UV bulb in enlarger?

[Greg]

When I was at RIT in the 1970s, I remember a professor and a few students attempted to construct an enlarger to use for alternative processes. They had the funds, and access to more equipment and technical expertise than most probably anyone of us could even wish for. Plus downstairs was a whole printing department who daily used high intensity UV light sources. I believe that the project was short lived for various technical reasons and problems.

[Tin Can]

I try to encourage experimentation

even now in post post post post foto

[j.e.simmons]

I tried it once with a CFL bulb in my Beseler 45MX enlarger. I only exposed for an hour and got a bit of an image on albumen. It does seem it would work with time.

[Drew Wiley]

UV enlargers have been commercially made. There are certain problems with bulbs bright enough to do the job quickly. There will be a lot of heat, potentially requiring a water jacket cooling system around the enlarger head. All the internal seals and gaskets have to be high-temp pure silicone, or the extreme UV will break them down rather quickly. And third, you have to protect your eyes with something like welding goggles. Sunburn risk too. It would be better to have a second, more ordinary bulb in place just for sake of focusing. The proprietary Fresson process uses a carbon-arc enlarger, a very old-fashioned option. Azo can be done with any reasonably strong halogen colorhead and a fast lens. CFL bulbs are just a bad joke all around, though I think specific UV ones are being made. See some of the older posts on this thread. As I recall, Jens did build his own prototype UV enlarger and put it up for sale, but ran into some legal issues safety-wise; it probably needed an automatic shroud to protect the operator from the light.

[j.e.simmons]

The photographer’s exposure to the light is an important consideration. I set a timer for all of my UV work and leave the darkroom during the exposure.

[neil poulsen]

I knew someone with such an enlarger, though I never saw it. It required a special quartz (I believe) enlarger lens. Indeed, he could print enlarged negatives onto pt/pd paper. But then, he began to use digital negatives.

[Drew Wiley]

Most EL Nikkor enlarging lenses are said to transmit UV better than other brands. But anything containing true quartz elements would have been very expensive to make, and no doubt quite rare now.

[bnxvs]

[Sevo]

When working at a poster printer, we had a enlarger in the silkscreen lab for billboard and truck side prints - modified Klimsch, difficult device with a high power (upward of 5KW) arc lamp and watercooled head with exhaust pipes to the roof, needed modifiers into the coating, huge (up to A0) negatives and lots of time even at the resulting relatively modest enlargements. Only one person in staff could run it without creating mostly rejects. A smaller solution will probably have the same problems at a smaller scale (or even more, as the lamp power will be limited by the available cooling). Where full size negatives are feasible, it probably is not worth bothering.

[Dr Klaus Schmitt]

If you use my work from my site which clearly states "All text and images carry my copyright and I do not allow to link to or copy / download from my site or any parts thereof without my prior permission." then AT LEAST quote my copyright!!