What is the difference between longwave and shortwave UV lamps?
True longwave UV lamps produce mostly longwave UV light; they have a filter which screens out most (but not all) visible light. “Blacklights” are an inexpensive way of producing longwave UV; they too have a visible light filter, but it is much less effective than that on a true longwave UV lamp. For most beginning hobby and display applications, “blacklights” work just fine. Longwave UV light is present in sunlight, and is not harmful to humans. Shortwave UV lamps come in two types – filtered and unfiltered. Unfiltered shortwave lamps invariably produce a lot of visible light in addition to the shortwave UV light; they are fine for germicidal applications, or tanning applications, but are largely useless in examining or displaying fluorescent objects – the visible light produced simply drowns out any fluorescence produced. Filtered shortwave lamps use a very expensive filter which allows shortwave UV through, but filters out almost all visible light; they are the ones which are used by
