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Mixing Green Beans with Brown
Part Four of a Five Part Tutorial on Fusing and
Compatibility
Click here to go to the
first part of this article.
If you don't
want to buy glass that the manufacturer has already tested for
compatibility, then you'll need to do the testing yourself. This isn't difficult, but it does take a few special
tools and a little time. Testing is the only way to know for
certain that the scraps of glass you have will work together without
causing cracks.
Testing for
compatibility requires a kiln, some scraps of glass to test, and
some polarizing film. Of these, the film is the one that's
unfamiliar to most people.
Polarized
film is a special filter that blocks a portion of the light coming
to your eye. Polarized filters are often used in photography to
reduce glare from water or heighten the contrast between clouds and
the sky.
They're
also used in Polaroid sunglasses, or in sunglasses that are
“polarized” but may not be made by the Polaroid company. (The
Polaroid company, now better known for instant cameras, got its name
when founder Edward Land discovered a new way to make polarizing
filters and used it to make sunglasses and similar products.
Needless to say, Dr. Land probably managed to stay awake during his
high school physics classes.)
I found my
first pair of polarized lenses by going to my local drug store and
checking out the sunglass display. I was looking for a pair of
sunglasses that was polarized and asked the clerk for the least
expensive pair of polarized sunglasses they had. We eventually
found a broken pair that was stashed behind the display. After
haggling on the price (we agreed on free!), I checked to verify that
the lenses were really polarized. This is done by stacking two
lenses on top of each other and rotating one lens while holding the
other one still. If the lenses are polarized, you will see the
amount of light that comes through change as the lens is rotated.
When one lens is 90 degrees from the other, almost no light will
pass through.
Once
you've found a polarized lens, you're ready to start compatibility
testing.
Click here for the final part of this series
-- how to do the compatibility test.
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Copyright 2005 Brad Walker.
All rights reserved.
This article was originally
written in 1999 and was one of a series that became the basis for the
Warm Glass website. It
has also been published in Common Ground: Glass, the
newsletter of the International Guild
of Glass Artists.
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