The terms to remember are:
1. Correlated Color Temperatures (CCT): a number expressed in degrees on the Kelvin scale. Warmer colors being a lower temperature and cooler colors being higher.
2. Spectral Power Distribution (SPD): the levels of each color wavelength in a light source. It ranges from the reds to the blues on the ROY G. BIV rainbow scale. The mixture of these determines the CCT.
3. Color Rendering Index, (CRI): a number express from 0 to 100 with the obvious scale values for showing the accuracy of color perception at a given CCT.

CCT and SPD work together to influence your eye’s perception of an object’s flavor. The CCT & CRI are related in that the CRI measurements for two light sources can only be compared if they have the same CCT. For example, the sun has a CRI of 100, yet a CCT of a cool 5800K. A 60w incandescent lamp also has a CRI-100, but is a warm 2800K. The color is rendered at an index of100 for both of them–it’s just the flavor that has changed.

Our interactions with the sun through the evolutionary process endowed our eyes with keenness at a higher blue color temperature. Even when our troglodyte ancestors hunted at night, the moon gave them a CCT of around 4100k. We are biologically configured to see clearer (discern colors and contrast) at these higher color temperatures, yet we find more comfort in a 3000k environment. Maybe we subliminally equate a warmer CCT with chewing on fresh mastodon around a nighttime cave fire.

Now, on to full spectrums. Full spectrum is a term used to imply a smooth spectral electromagnetic distribution. They are usually fluorescent, but are available in incandescent too. Their characteristics include:
1. Marketing campaigns that tout a departure from artificial light.
2. Having a CCT of 5000+, bringing the clarity of natural daylight.
3. The promises of better color, productivity, plant growth, higher profits and tooth decay prevention.
4. Emit UV radiation.
5. Have a high CRI, usually above 90.

Full spectrum lamps are tuned more toward our eye’s sensitivities; yet do not render colors with the accuracy of the sun or an incandescent lamp at their native CCT. Their CRI is below 100, but high enough not to make much of a difference. Full spectrum sources do, however, bring a broader SPD to your tasks; therefore, a viewer may experience better discernment between colors.

Yet, according to the Lighting Research Center, there appears to be little evidence to support most of full spectrum marketing claims. It appears that full-spectrum light sources will not provide better visual performance than similar sources under most circumstances. The UV radiation is also something to think about since prolonged exposure may damage artwork pigments. Furthermore, the jury is still out on whether the promised psychological benefit of ‘well-being’ is from the actual SPD or the clever marketing approach dubbing them “natural” lighting.

In short, FSL lamps are good, but you may be able to save money by dialing in your CCT and CRI with a standard lamp to what you require of it.

Here’s a link to the Lighting Research Center’s work on full spectrum lamps: http://www.lrc.rpi.edu/programs/nlpip/lightingAnswers/fullspectrum/lightSources.asp
Another link to an SPD chart of two lamps.
http://en.wikipedia.org/wiki/File:SPD.png

I’m a bit confused though. Your standard incandescent light bulb is nowhere near full spectrum. The near full spectrum bulb I have is, I believe, fluorescent and I’ve only ever seen them in this form.

Congratulations on your blog! You are so right about stepping back to look at the big picture. I’ve tried to do more of that with this darned recession and it actually helps me to keep my perspective. When I remember that this too shall pass and if I keep plugging away with my marketing plan, regardless of how things appear at the moment, I actually feel really hopeful! So I totally agree with what you’re saying. Thanks!