AIEL
Purchase Guide
|
ULTRAVIOLET
|
|
|---|
Here is a short guide to blacklight sources. This is not
a complete discussion on ultraviolet. If you wish to know
more,
Contact Atlantic Illumination.
For additional information, consult the manufacturer's
literature, or try a local library (especially university
ones). Se our Backstage Pass.
for manufacturers.
Atlantic Illumination sells a variety of UV products.
THE FOLLOWING MAY NOT BE REPRODUCED
WITHOUT PERMISSION FROM THE AUTHOR ©
The incandescent source is an ordinary light bulb with a dark purple coating. These fail to give off much of the ultra violet frequencies because there are few radiated at that end of the spectrum from these sources. The incandescent blacklignts typically have a short life - usually only a few hundred hours. Also, some older styles hold in a lot of heat and can become dangerously hot.
For stage or club use, these are not recommended except as a purple light bulb. Home users may get a small effect if the source is placed close to a blacklight poster. However, given the short life, possible excessive heat, and better effect from even a small fluorescent source, they are not recommended to anyone except those on the smallest budgets.
The fluorescent source is the most popular and cheapest, overall. Wattages range from 6 to 40 watts with sizes ranging from compact source, through T-8 up to T-12 bulb diameters. The compact and 15 or 20-watt sources are recommended only for home use, except for sign or point lighting where a small fixture at close range will suffice. The 40 watt lamps, especially in pairs or quads, are required for stage or large area lighting.
Home users can expect an excellent effect from the less expensive, 15-watt, T-8 lamps. Life is much greater than the incandescents: Typically 7,500 to 9,000 hours for the lower wattage lamps, on up to over 20,000 hours from the 40 watters.
Be aware that off brands typically last far fewer hours, and usually do not give as much UV per watt. Also, the cheaper lamps often have poorer filters and allow much more visible light through. This dilutes the effect greatly.
Mercury vapour lamps are a larger version of the fluorescent, which operates also using the mercury vapour principle. They come in small PAR 38 sizes on up to the large 400 watt models. These are recommended for large stage productions. They are expensive but can put high levels of UV on an area. The disadvantage is that they can take up to seven minutes to reach full output, as opposed to fluorescents which are instant on, or nearly so, depending on the lamp and ballast used.
In all cases, be sure to get filtered tubes. They block up to 80% of visible light emitted by the source. Using non-filtered tubes is cheaper, but it's like having a white light on, thus the effect is diluted.
Germicidal lamps are never to be used for entertainment lighting. They are meant to kill bacteria and thus skin and eyes will be harmed when exposed to a germicidal lamp's rays.
|
BLACKLIGHT
|
|
The incandescents and PAR 38 mercury vapour lamps use a medium screw base socket. All lamps, except for the incandescent, require a ballast fixture. The ballast is in part a transformer/coil used to start the lamp and control current through the lamp. If you are buying a ballast fixture, you must buy a Sound Rated `A'. These emit low audible noise and also transmit less noise into audio systems, which will likely be used near these lights.
You should buy a fixture with a white enamel or polished reflector. These direct/reflect the light towards your intended area and control spill. Fixtures with a black reflector may look nice but they reduce the potential intensity of blacklight rays striking fluorescent objects, and thus diminish the effect.
Larger mercury vapour fixtures come with an integral ballast and typically a 250-watt lamp. They use a larger-diameter filter at the front of the fixture and give a high intensity, wide-coverage beam. The disadvantage to these types of fixtures is that they take 4 - 7 minutes to come up to full intensity.
Return to the
Purchase Guide
Table of Contents
