Postulate this: If a tungsten light bulb filament gives off black body radiation how do they make black light bulbs (the woods glass type) and "halogen" lights that give off UV? The UV catastrophe problem says that you can't do that. I have a feeling "black light" may not be UV but rather extreme purple that our eyes can't see, but its still color light right before the photon has enough keV to ionize. This would be the same trick in woods glass fluorescent black light tubes, as the envelope would have to be quartz to let out UV, or does silica glass pass UVA just fine? Wouldn't the best black light be a fluorescent quartz glass tube with a UVB/C filter that also cuts most of the shorter UVA wave lengths?
Fun Story, my bed room as a kid had four 4' black lights on the edge of the ceiling with tin foil reflectors on the wall. The room looked normal day or night, but when you turned on the black lights you could see the walls were painted in laundry detergent antifreeze, dilute highlighters, and some other toxic chemicals that look clear under normal light. We used to give our friends way too many hits of LSD or mushrooms bring them in the room they saw many times in ordinary light, then turn on the black lights and watch their minds explode!!! Wish I had pictures film cameras didn't show that stuff well or rather not easily like a digital camera would.