This combination of additive light synthesis using RGB led clusters with absorption based pigments for reflecting light in a painting poses some serious problems for artists wanting to use LED based lighting to accentuate particular paints in their work -- if they choose a paint that reflects in the wrong colors, they could do a lot of work and end up with something that looks not at all like they intended. With this in mind, the first step in the project was to build some prototype LED lights and use it to characterize the various pigments on the market.
The first light for making these tests was built in October 2006 and used LEDs of six different colors (red, amber, green, cyan, blue, and royal blue) to test the reflective performance of various paints. Using commercially available, pure pigments (mixing is a bad idea for this sort of artwork), we identified specific brands and colors which responded fairly closely and strongly to a specific LED wavelength and not to the others. These pigments are ones, therefore, which reflect with only one strong peak instead of multiple or broad reflection peaks. We also decided that incorporating blacklight UV LEDs into the fixture would allow for some very exciting possibilities through the use of fluorescent paints.
Essentially, this six LED test system acts as a "poor man's" spectrophotometer that measures directly the reflective response of a pigment at precisely the frequencies that the LEDs are emitting, measured qualitiatively by the eye. If a pigment on the paint splotch shines brightly when the green LED is on, but not when either the cyan, or amber LEDs are on, then it has a "narrow" reflective band for the purposes of this art.
In practice, finding green paints which actually reflect green light was extremely difficult, far more difficult than finding either red, blue, or orange colors. So, if you've been using RGB LED clusters and have found that your blue and reds show up great, but your greens are dull and flat -- you're not alone! It's the fault of the paints, not your technique. Check back later for a list of pigments we've tested and found to work the best with producing greens.
The next step was to begin creating artwork. This process was long, but very productive. In this time, I designed and built a new, more professional light fixture which I call the Ultrabright Illuminator (described more below), and we've had a few small art shows where the fixture and artwork is displayed.