As you know I used to work in a photolab. My job was to tune the printers. These used FAL and FAD halogen bulbs rated at 500 watts and 40 hours. As the bulbs aged they changed brightness and color. I would run a negative test strip develop the photograph then measure the amount of light reflected off the photo with a transmission densitometer. Toward the end of their life with less tungsten and more current the bulb would melt. The printers had two dichroic filter that I could adjust to change the color of the light before it went through the negative then the printer had three color blocking filters that would snap into place once the printer thought it had enough of each color. The human printers would view the negative and make color corrections with a series of buttons. One of our printers got skin cancer on the underside of her nose. This was after the light had bounced off several walls of aluminum passed through 5 filters the film and a piece of glass. We added UV filters to the mix. She is fine. The newer machines were computerized and didn’t need a human viewing the negative. The inspectors had an 8 inch magnifier with a circular fluorescent light and two regular bulbs.
Yeah, I got an ancient fluorescent dye tracer and the thingy was a 50W halogen bulb with silvered-glass filter that would pass the 1% of UV that would sneak through after blocking visible light.
People don’t realize that even hotwire blubs still pass some teeny amount of UV.