Blacklights are made with a glass that filters out
most visible light, creating a glowing effect when used with
blacklight posters and other special materials. They can be
especially useful in highlighting ghost scenes (FCG?) or in
concealing Black on Black effects.
Types of Blacklights
There are several different types of Blacklights
available on the market. It's important to know the differences for
safety and to get the best effect for your haunt. Make sure that any
UV sources used for your haunt fall into UV-A, preferably 345 to 400
nm. Lamps sold for entertainment purposed probably fall into this
safe area. They should be specifically marked "black light"
(Example BL in the tube designation (F40T12/BL) means blacklight.
There is also a BLB designation that is also a blacklight but the
effects produced are diminished.
Avoid UV lamps designed for rock-hunting; many
minerals fluoresce under short-wave UV, and rock lamps are designed
accordingly (some are switchable between long and short wave). .
Short wave UV can be dangerous and is primarily used for certain
germicidal applications. There are also white colored UV bulbs like
the type used in tanning beds or even Lizard cages. Never use bulbs
not specifically designed for entertainment purposes.
Some items that Flouresce
Many other substances fluoresce naturally under
black light, including liquid detergents, quinine (in tonic water),
urine, and some types of paper money.
Some of the whiteners in detergent work by making
your clothing a bit fluorescent. Even though clothing is rinsed after
washing, residues on white clothing cause it to glow bluish-white
under a black light. Blueing agents and softening agents often
contain fluorescent dyes, too. The presence of these molecules
sometimes causes white clothing to appear blue in photographs. The
best example of this is RIT Super Whitener Fabric Dye
Whiteners and some enamels contain compounds that
glow blue to keep teeth from appearing yellow.