Ever wonder why some materials glow in the dark and some do not? Most materials that glow in the dark have phosphors. These are any of the known substances that emit visible light triggered during radiation. They convert the black light from the energy in some sort of UV radiation into the known visible light.
Black light bulbs are another classification of fluorescent bulbs that have one phosphor element inside its dark glass envelope coated with nickel oxide. This dark envelope is called Wood’s glass which is effective in blocking the wavelength of most visible lights. Black light blue bulbs are lamps that have normal glass envelopes treated with a thin layer of a certain UV filtering substance coated in their exterior. Their designs usually range from a single tube, twin tube, spiral, and common incandescent bulb. Lamps that do not have filtering material applied in their glass envelopes are called bug zappers.
Common black light bulbs absorb UVB and UVC through the phosphor coating of its glass tube. Only UVA light could pass through its black glass tube. Similar to the ordinary household light bulbs, incandescent black light bulbs use filters to absorb the light emitted from its heated filament. In both tube and incandescent-type black light bulbs, the UV lights emitted react to the external phosphors which would glow provided that the UV light is directed to them.
Aside from making fluorescent posters and people look “cool,” black light bulbs are used for practical functions. Analysis of crime scenes by forensic scientists through distinguishing fingerprints is made easy by the fluorescent dye in the dust which would glow using the black light. Bodily fluids such as urine and semen can also be identified under the black light. In machineries, repairmen may also employ fluorescent dye to detect invisible leaks.
Counterfeit money and forgeries of antiques may also be identified under the black light. Many countries insert invisible fluorescent strips in their bills which could not be copied by those who produce counterfeit bills. Phosphors which are highly present in modern paints will also indicate false antiques because older paints would not contain them.
Black lights are also used mostly for artistic and decorative lighting effects. Halloween decorations would pale without the much needed horrific effect of black lighting. Nightclubs would also be unappealing without the flashy cool lighting. Try walking down the busy avenues of the city and you might just be surprised of the many different ways that black light have given color to luminous materials that would not have been appreciated in clear day light.