We have been providing black light for over 25 years. The effect is awesome cool science, but often misunderstood.
Black light is actually invisible light [ULTRAVIOLET] just below the visible spectrum:
Black Light FAQ:
Q. How does black light work?
A. Under black light, phosphors convert the invisible UV light they receive into visible light. This is called "Fluorescence".
Q. How much black light do I need?
A. Entirely depends on: 1.) venue size, 2.) # of guests and 3.) the strength of glow effect you wish to create. Contact us for assistance.
Q. What is the range of visible light?
A. 380 nanometers (nm) to 740 nanometers (nm).
Q. What is the range of proper invisible entertainment black light?
A. 350nm - 380nm. *Centered on a 368nm peak*. This is just below visible light range.
Q. Is black light safe?
A. Only black light between 350nm - 380 nm wavelength (the top end of UVA wavelength), is considered safe at entertainment levels.
UVC is used for medical instrument sterilization for example and most certainly not the type of UV Light you want at your next party.
Q. Where is the best location for maximum black light glow effect?
A. The best location for black lights is hanging above your subject(s), the next is shooting from front/sides on light stands.
The floor is only useful if you want black light on your shins.
Q. What items will glow under black light?
A. We cannot guarantee your items will glow (fluoresce) but generally speaking:
Fluorescent clothing, white cotton, fluorescent paint, tape and black light makeup will glow under black light.
Washing clothing in detergent with phosphates *may* give you a small glow boost [Hint: that is what makes whites 'brighter'].
Q. What are examples of a 'imitation' black light?
1. Any "black light" fixture not specifying their output in nanometers (nm).
2. Any fixture not producing wavelengths peaking on/around 368nm.
These fixtures cannot effectively produce lower than 390nm plus they create excess visible blue light.
The amount of true UV created is minimal in comparison to real UV fixtures.
In short, you will require more of these fixtures and will end up with excess blue/purple light which subtracts from the real glow experience.