BLB lamp

There are incandescent bulbs made with deep violet-blue bulbs which largely filter out visible light. Longer UVA wavelengths get through the glass and are not blocked by the dark colored filter dye. Most visible violet and some visible blue light get through, as well as a wide range of infrared and the longest, less visible of visible red wavelengths. Some traces of other visible wavelengths get through.These bulbs are a convenient source of some UV to cause fluorescent paints, dyes, and other substances and objects to glow. Most of such fluorescent objects (especially magenta, red, pink, orange, yellow, and green ones) also glow from visible violet and blue light.