I've heard it called all kinds of things.... Dichronic, dichromic, or even dichromatic glass. So just what is this glass that folks just can't seem to remember the name?
The word dichroic literally means 'many colors'. Of these many colors artists are mostly concerned with two main types. These can be classified as both transmitted color and reflective color. Transmitted color is the color you see when you look through a piece of glass. Reflected colors are the colors that bounce back to you looking at the piece directly. (If you are looking at a piece of black backed dichroic glass that has already been fused, what you are seeing are the reflected colors.)
These colors come about as a result of multiple micro-layers of metal oxides that have been deposited onto the glass. NASA developed dichroic glass for use in deep space exploration, satellite mirrors and space suit visors. It has since moved on to be used various other applications, including art. Multiple ultra-thin layers of different metals (gold, silver, titanium, chromium, aluminum, zirconium, magnesium, silicon) are vaporized at extremely high heat in a vacuum chamber along with quartz crystal. These vapors adhere onto the surface of the glass and bind together on a molecular level. The brilliant colors are determined by the type of metal used in the vaporization process.
It's hard to believe that these thin layers of oxides have a total thickness of only 3-5 millionths of an inch! Certain wavelengths of light will either pass through the layers or be reflected, causing an varying array of color to be visible.
After fusing, the color will shift towards the left on the visible color spectrum from its pre-fused state, and depending on the thickness of the dichroic coating, the amount of time and temperature under which it was fired, the number of firings, and the type of base glass used will determine the color that you actually see.
Ok - so that's dichroic glass in tech speak... While I personally find the process facinating, I have to admit that when I first saw the stuff I really just reacted to it on a viseral level. You know, something along the lines of, "Oooo, pretty! Look how shiny...I want it!" I guess if I'm really honest with myself, I must admit that I still react that way even after years of working with it!
