Color Temperature and Color Rendering Index

To choose the right fluorescent lamp for a specific application, consider two things: (1) Color Temperature, and (2) Color Rendering Index.

Color Temperature

Color temperature is expressed in degrees Kelvin.  For example, natural daylight is approximately 5250 degrees Kelvin (about the color temperature of a Service Guaranteed Triten 50 fluorescent).   Fluorescent lamps with lower color temperatures look red, and fluorescents with higher color temperatures look blue.  This makes sense if you imagine an iron bar being heated.  First it gets "red hot."  Then, as it gets hotter, it becomes "white hot."  Finally, it becomes "blue hot," like a flash bulb.

The Color Rendering Index (CRI)

CRI is a numerical system that rates the "color-rendering" ability of a fluorescent light in comparison with natural daylight (CRI of 100).  So, a lamp with a CRI of 90 shows colors more naturally than a lamp with a CRI of 65.

Good Color Rendering

Good color rending is critical in situations where people must appear nature or products must look appealing.   In office and factory applications, high color rendering can increase visual clarity, create a more productive environment, or make close color matching possible.

The color of an object is determined by the light it reflects.  For example an apple is red because it reflect light energy in the 628-770 nanometer, or "red," range.  If a light source is deficient in that range, there will not be enough light for the apple to reflect, and it will appear dull or off-color.

To understand this, think about Cool White Lamps.  They were developed in 1937 and were great for their time.  Since then, however, there has been little improvement to them and everyone knows they are not good color redesign lamps.  That is because they are high in yellow output, but deficient in other pats of the visible spectrum.  So, Cool Whites do not allow most objects-and especially skintones-to reflect their true colors.

Very often, color-balanced "natural" light will be appropriate.  Other times, the main consideration will be to create a certain "atmosphere," such as warm lighting in settings where people gather, like restaurants or conference rooms.  Once you have decided on the desired atmosphere (daylight, cool, neutral, or warm), it is just a matter of determining how much light (lumens) and what color rendition (CRI) the situation requires.

In addition to visible light, sometime the light you do not see it critical to an application.  Service Guranteed's Spectralite full-spectrum fluorescent lamp provides invisible ultraviolet radiant energy, as well as the complete range of visible light.  Full-spectrum fluorescent lamps have been successfully used for indoor gardening, to keep healthy pets, and in the treatment of Seasonal Affective Disorder (SAD).