As far as man-made lights go, fluorescent lamps are second only to the various discharge lamps (metal vapor, HID, etc) for UV production, and these are only exceeded by sunlight.
Fluorescents produce UV in their internal arc, and the coating on the inside of the lamp absorbs the UV and creates visible light. UV-filter sleeves filter about 99% of the UV.I'm reluctant to say how much UV is in the spectrum of fluorescent lamps because I can't remember how it's specified, so ignoring units, I think it was in the few to several percent range...enough to cause long term fading of artwork and fabric, but I can't say how much for cyanotype. In general, fluorescent lamps should be considered a significant UV source. Murray
