What are Phosphorescent or Photoluminescent Pigments?

Phosphorescent or Photoluminescent are Luminescent Pigments or powders that can give off light. Unlike conventional colorants, LUMINESCENT pigments are not primary light reflectors, but sources of light. They possess the property of absorbing certain types of radiant energy (usually below 4000A and not visible to the eye), and converting this radiant energy into longer wavelengths in the visible spectrum, and emitting it as light. The selective wavelengths, thus emitted, produce the sensation of colors or light.

When the emission of luminescent light ceases with the removal of the exciting energy, the luminescent material is called FLUORESCENT. If the emission of light continues for an appreciable period of time after the exciting energy has been removed, the luminescent material is known as PHOSPHORESCENT or PHOTOLUMINESCENT, and has the property of "glowing-in-the-dark".

The ability to absorb light, and then release this light in a decay pattern is known as PERSISTENCE or AFTERGLOW. Different types of phosphorescent pigments emit light in different decay patterns. The unit of measurement for persistence is MILLICANDELA per meter squared or mcd/m2. Some emit fairly high amounts of light initially, and then continue to emit light for 5-8 hours. And still other types will emit light for more than 17 hours before becoming too difficult to see with the human eye. These longer lasting afterglow pigments can be used to "light-the-way" in total darkness in safety signage and paint.

All of the Phosphorescent or Photoluminescent Pigments have their individual "daylight" color of whitish yellow to yellow/green. This "DAYLIGHT" color can be changed by adding organic fluorescent pigments with wavelengths greater than itself, or greater than 520nm, (NANOMETER, is the wavelength at which the emission color is emitted). Typically these pigments are added to clear "vehicles" or inks, paints or plastics.
The EMISSION color, is the color that our eye perceives when activated by UV light.

Please contact USR Optonix to discuss your specific application.