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The Creative Can of Beans
This is part two. It
probably won't make sense unless you've read part one.
Click here if you need to bring some sense
into your life.
When we last left our lonely can of beans,
we'd emptied the contents, heated the can in the kiln, and the
covered the outside surface with kiln wash. Now we're ready to
get to the glass.
Root
through your scrap pile and find a piece of glass that's bigger than the can
you're using. You want a piece that can cover the bottom and extend
over the sides as well. About eight or nine inches is fine for the
average can of beans. (I know, I know, this is is a little large
for a piece of scrap, but bear with me. We'll learn how to use
small scraps in a future can of beans tutorial.)
It doesn't matter if your piece of scrap is
perfectly square. It doesn't even matter if it's a circle, a
triangle, or even an odd concoction the shape of Alaska. I like
circles and ovals best, but you can try any shape you'd like. Just
about any type of glass works, from baroque and wispy to cathedrals
and textures. Even ordinary window (float) glass can be used.
(Paint on it if you'd like.) Different shapes and glasses will give
you different results. Experimenting is good.
Is your can cool yet? Is the kiln wash dry?
If not, just wait a few more minutes until it's ready. If you got
distracted, it doesn't hurt to leave the can to dry for a day or
two. But whenever you're ready, just place the can back in the
kiln. Bottom side up, as before. Center the scrap of glass on what
is now the top (used to be the bottom) of the can. Since the glass
is larger than the can, it will extend over the edges and stick out
in all directions. You can use a ruler if you're really finicky,
but absolute centering isn't necessary. Sometimes the best results
come from scraps that are off center.
Once you're happy with the placement of the
glass, shut the kiln door and turn it on. As when you were kiln
washing the can, you can fire at a fairly high rte. You should be
able to fire at a rate of at least 10 to 15 degrees Fahrenheit (5 to
8 degrees Celsius) increase per minute, and maybe even faster. (For
those who think in hours instead of minutes, that's 600 degrees
Fahrenheit or more per hour.)
Firing slower is ok, too. But most of us are
impatient and want to fire as quickly as we can. Fortunately, with
one layer of scrap glass we can fire pretty fast. Thicker glass
requires slower firing. Anyway, keep firing until the temperature
reaches around 1200 degrees Fahrenheit (650 Celsius). It should
take about an hour, more or less. (Maybe you can eat some canned
beans while you wait.)
If your kiln has a peephole, now is the time to
look inside. It's best to wear protective glasses. Not those clear
plastic things you wore in chemistry lab (or was that wood shop?),
not even those expensive didymium glasses some glassworkers use:
the best glasses for kiln-workers are ones that shield your eyes
from infrared rays. Frequent exposure to infrared rays, which glass
gives off once it reaches around 900 degrees Fahrenheit (480
Celsius), can cause
cataracts or other eye problems. To prevent that, wear glasses that
block infrared rays. Welder's #3 lenses (or even # 2.5 or #2) are
just about right, and very inexpensive. Many people claim you can
get away without using glasses, but some people think you can eat
three-month-old tuna salad, too. You can, but sooner or later it
will catch up to you.
If you peer inside the kiln (glasses on,
right?), you'll see that the glass has taken on a red glow. The
edges of the glass – those parts that were extended over the edge of
the can of beans – may have started to droop down. If not, just
wait. (Gravity is your friend.) Holding the temperature at around
1200 degrees will cause the glass to "slump" or "sag" over the can.
Some people call this "draping" because of the way the glass seems
to drape around the edges of the can, but the keep thing to remember
is that the longer you "soak" at this temperature, the more the
glass will droop.
With some glasses, such as "float" or typical
window glass, slumping often takes place at a slightly higher
temperature (around 1350 to 1400 Fahrenheit / 750 Celsius). Some people prefer to
slump at 1250 and some prefer to slump for a few minutes at a lower
temperature (say, 1150F / 620C) and then quickly raise the temperature
into the 1300's. There aren't quite as many different slumping
temperatures as there are ways to eat a can of beans, but there's
enough variation for you not to worry if your slumping works best at
1250 and mine at 1200. The key is to learn what's best for your
glass, your kiln, and your way of working.
Once you're happy with the way the glass has
slumped over the can, you can stop soaking and begin the process of
cooling down. That's the subject of the third (and final!)
part of this three part tip.
Click here to go on to the
final part of this
tip.
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Copyright 2005 Brad Walker.
All rights reserved.
This article was originally
written in 1999 and 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. There are at least two more parts, all coming
soon to a computer near you.
If you want to learn more about
fusing and slumping glass, check out the Warm Glass tutorial at
www.warmglass.com/basic.htm
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