Fusing is an ancient art process dating
back to the Egyptians and Romans. Most
historians say 2000 B.C. Although the first
2000 years of the 4000 year existence of
glass forming was quite strong with the use
of fusing, the last 2000 years are quite
devoid to the point it almost became extinct.
Over the last 15-20 years, it has been
brought back to life. Between the limitless
possibilities of fusing (bending and glass
forming) and the lack of information, this
area of glass is for those who enjoy
experimenting.
The term "Hot Glass" refers to working with glass in its molten form: fusing is one. To fuse means "to join together by the application of heat" usually in a kiln. The glass artist takes pieces of cut stained glass, arranges them in the desired design placed on a prepared kiln shelf and heated to the desired temperature. The higher the temperature, the more the glass melts together from a "fused to stick" stage, which is a raised design with all edges rounded to a "full fuse" where the glass melts together to form a flat surface.
Combing
At a higher tempature (usually around 1700+
degrees)
is where a technique called "combing"
is done. This is one of my favorite
techniques. When the surface of the glass is
liquid enough to be moved with a combing rod.
This concept can be related to the swirling
of food coloring in a cake batter. I have a
combing rod that is about 18" long (metal)
with a pointed hook on the end and a wooden
handle. When you do this technique safety is
extremely important! Wear only cotton
clothes (others fabrics can actually catch on
fire and melt to your skin) If you have long
hair, tie it back. Cover your arms with long
sleaves and wear a good pair of kiln gloves.
And above all wear eye protection! The heat
that rises up will burn your eyes if you dont
have on glasses.
Now having all that said....here's the fun part. The best design for combing is to cut strips of glass and lay them across a base piece. I usually make my base piece a circle which can later be slumped into a plate. Once you have gotten your glass piece up to the right temperature you are ready. TURN OFF THE KILN!! Open the lid (helpful to have a friend do this-good for moral support too!) "Draw or comb" a line across the strips, be careful to not go too deep. Practice tells you how deep to comb. Close the kiln lid. Turn the kiln back on, and bring the temperature back up.
Usually you only have time for one "comb" before the kiln and glass cool down. If the rod sticks in the glass, or won't comb then it is too cool. If the glass piece moves on the shelf it is probably that you are combing too deep. You can change the whole shape of your glass piece since you are at such a molten stage. It is also helpful to have a bucket of water to dip the combing rod into between combs to cool it down. Each time you comb you MUST remember TO TURN OFF THE KILN! Then when done to turn it back on. It is frustrating to be waiting for the temperature to get back up and realize you FORGOT to turn the kiln back on! !LOL
Coefficiency of
Expansion
Since fusing is actually
playing with the
chemistry of the glass, it isn't quite as
easy as it sounds to have a finished piece of
glass that won't develop cracks. Stained
glass when manufactured has different metals/minerals
added to create the different colors.These
melt and, more important, return to a solid
form at different temperatures, especially
the "hot colors" such as reds, yellows and
oranges. If the expansion points are
different enough, cracking will form, either
when cooled or as long as 6 months to 1 year
later. The way to tell if your piece cracked
due to incompatibility is the fractures will
follow the boundries of where the glasses are
fused. In contrast fractures will randomly
cross the boundries if the glasses are
compatible but improperly
annealed.
All
manufactored glass has a COE
number (coefficiency of expansion), this
number is determined by the amount the glass
expands in a one degree temperature rise.
The measurement is so small all the decimal
zeros are dropped to simplify the number. All
glass should be tested, unless it is sold
"tested compatible". (even then you might
consider testing if you are going to be
putting alot of work in your fused piece.)
The fusing compatiblity range is plus or
minus 1.For example Spectrum glass COE is 96
a safe range would be 95-97. I feel strongly
about testing, maybe because I fuse mainly
with Spectrum glass, and even tho it is very
compatible it isn't sold "tsted compatible".
Here is a list of manufactored glass
COEs:
104 Moretti
104 Millefiori
96 Spectrum
96 Uroboros
and
90 Uroboros
90 Bullseye
89-92 Bottle glass
83-87 Plate float glass
35 Duran
33 Northstar
32.5 Borosilicate /Pyrex
Etc.
To understand the price of the fused glass,
remember a good fused piece has many hours of
testing, experimenting and experience in it.
When a fused piece has been slumped, this is
a separate procedure in the kiln at a lower
temperature. Each time a piece of glass is
put in the kiln, the risk of losing it
(breaking) is very possible. This can be
discouraging. to some artists, to others it
is all more rewarding with that finished
piece that did turn out right! Many of the
more advanced fusing artists around the
country state that they have a 50-60%
survival rate.
Designing for fusing, an artist is only limited to his imagination. Many cuts that are not possible structurally in the traditional forms of glass (leading/foiling), are possible in Fusing. There is something magical about hot glass. For thousands of years, people have been fascinated by both the process and the results of forming glass. May this information do the same for you.
I hope to add photos of my fused glass. However if you check out the photos The Aquarian on photos page 1
Kat's quilt on photos page 2 have fused pieces incorporated in these leaded panels. And if you go to Fusing with Spectrum Glass you will find more information on fusing, as well as Firing and Annealing Guides.
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