Dichroic glass

Dichroic glass is made by depositing microscopically thin layers of metal oxides on extremely clean glass in a vacuum chamber causing light to change colors as it is reflected and/or transmitted. The technology, called "Thin Film Physics", was originally discovered when NASA while looking for heat shielded glass for the space shuttle and has evolved from our aerospace programs into the art glass field.

The technical definition of dichroism is an optical effect observed in crystalline materials, in which different colors are seen when the crystals are viewed in different directions in plane polarized light. In an anisotropic crystal, light is absorbed depending on its direction of travel through the crystal. Anisotropic crystals show a change in color when they are viewed in different directions and may produce a number of different colors: known as pleochroism. When only two colors are observed, it is called dichroism.

Dichroic Art Glass is made from materials that are completely transparent, meaning they do not adsorb any appreciable light energy in the visible spectrum. This lack of adsorption is responsible for the clean crisp colors evident in dichroic glass. Dichroic coatings transmit certain wavelengths of light, while reflecting others, thus creating an interference-effect similar to the iridescence observed in nature's fire opal, dragonfly wings, fish scales, bird feathers and even the color seen on an oil slick on water.

The Process: The glass is first optically cleaned in a meticulously clean room. The slightest speck of dust can mar the coating. The glass is polished, then cleaned to the molecular level with several types of solvent alcohol. It is fastened to an arm in the top of a specialized furnace chamber. The oxides are placed on the bottom of the chamber. Air is removed with a high vacuum pump, creating an environment similar to that of outer space. The metallic oxides are vaporized by an electron beam, and the rotating glass target is evenly coated with many extremely thin film layers of elements, such as titanium, magnesium, zirconium, beryllium, chromium, selenium, yttrium and tin. The resulting color is determined by the individual oxide compositions and the coatings sequence. The process is all tightly controlled by a computer.

Each color is individually engineered. magenta transmission requires 19 layers to remove the light we wish from the transmitted spectra. Not all colors are so easy to achieve, green transmission is just the opposite of the magenta. To get a green transmission, requires 49 layers. This sounds like a big, thick coating, but if you add all those layer thicknesses together, the total coating thickness will still be less than one thousandth of a millimeter (3 to 5 millionths of an inch).

The whole process time required in the machine is from two and a half to four hours, depending on the structure. Obviously creating dichroic art glass is anything but simple. There are literally hundreds of considerations that must be taken when designing a coating structure. This is the reason dichroic glass is so very expensive.

A glass artist then uses partial sheets of the laboratory created dichroic glass adding it to other glass, including other dichroic glass, creating individual artworks like vases, plates, glasses, etc, including jewelry cabochons which are subsequently set in precious metals creating individual art items such as these pendants.