Dichroic Glass
It was a case of love at first sight, followed quickly by "How did they
do that?" I was hooked, then I researched. In brief, this is what I
found out:
To start at the very beginning, the first dichroic glass was developed
over 100 years ago, but it took the space industry to turn it into a truly
useful product. Yes, NASA
found its unique properties quite beneficial as filters on the windows of
the various space vehicles, and they developed the modern process for making
it, which made it economical enough for the artist who also found it unique
properties to their liking. And, economical is a relative term - the stuff
is still quite pricey, due primarily to the way in which it comes into
being.
The manufacturing process consists of depositing
many very thin layers, most often one atom thick, of rare metals on the
surface of a piece of glass. This is done
in an ultra clean environment in a special
high-vacuum chamber. The materials to be
deposited are placed in a cup in the bottom of
the vacuum chamber and bombarded by an intense
electron beam. This beam vaporizes some of the material which then coats on the sheet of glass.
The glass substrate can be of just about any variety. So, when talking about
dichroic glass, you are actually talking about a very thin coating on glass,
and the actual types of glass may vary. For example, I use only Bullseye
Tested Compatible glass. No problem with the dichroic - I just make sure
that the dichroic I use is on Bullseye Tested Compatible glass. If I used
Spectrum 96, instead, I would just make equally sure that the dichroic I
used was on Spectrum 96 or was compatible with it.
The word "dichroic" means two colors. The two colors refer to
the transmitted color and the reflected color of this wonderful coating. For
example, a piece of dichroic glass that reflects gold will be blue if you
look through it. To make things even more interesting, the colors shift when
the glass is heated to fusing temperatures. So, a piece of glass that looks
gold when light shines on it before it is fused, will end up reflecting
green after it is fused - usually. I still have the occasional surprise come
out of the kiln.
In addition to dichroic glass, I also use iridized glass extensively.
This is another coating using a completely different process and completely
different materials. It results in a finish that is more matte than dichroic,
but that adds still another layer of sparkle to the finished piece.
