Making Fused and Cast Art
aka Kiln-Fired Glass,
aka Warm Glass
Glass used for Kiln-Fired Pieces MUST be made from glass which
has the same coefficient of expansion (COE), meaning it expands and
contracts at the same rate in the kiln and after-wards.*** We use
only Spectrum 96 and compatible (COE 96) glass.
Design & Cutting
An art piece, from a functional bowl to a pair of earrings, is
designed by the glass artist. From that design concept, a pattern
may be created. Pieces of specific glass are cut to fit that
pattern. Usually there is more than one layer, and often several
layers, to any one piece. The pieces are stacked and often glued
together for firing.
The glass is then fused into one solid piece in a kiln at
temperatures between 1480-1500 degrees F. for a full fuse (slightly
less for tack or contour fuses).
Slumping and/or Draping
Except for some jewelry pieces, coasters, etc., most pieces are
kiln-fired again, usually in a mold to give shape to the piece at
temperatures 1240-1300 degrees F.
Other types of kiln-fired glass, such as casting or pot-melting
require firings in the 1700 degree F. range.
Before, during and after initial firings, pieces may require
cold-working, a term which includes grozing, grinding, sandblasting,
polishing and other techniques before a next-stage firing, including
fire-polishing to provide a fine finish. Some pieces require
multiple firings and cold-working before completion.
And there you have your art glass piece!
Why not recycle glass?
The glass artist can recycle bottle glass as long as all glass in
each piece comes from the same bottle or from identical bottles from
the same manufacturer or if only one bottle is used per project. And even then, results can not be guaranteed
(due to varying COE's). Likewise, "plate" (window) glass may be
reused as long as each new piece is made from a single piece of
glass. A major frustration to all glass artists.
After attending a "Fusing
with Recycled Glass" workshop with noted glass expert Brad Walker in
August 2011, we have been "playing" with using recycled tempered
glass; see the results at the bottom of the
Pot Melt Log page.
***This type art glass is very expensive ranging from $6 per
square foot for clear single thickness glass to $26 or more per
square foot for specially colored or textured glass. Dichroic (metal
coated) glass can range from $115 to $190 (and much more) per square
foot. Dichroic glass is therefore usually used in jewelry or as an
accent in larger pieces. The cost of the glass is usually the
greatest single cost in the creation of any art or cast glass piece.
Making a 6” Fused Glass
page for larger versions)
Step 1 – Create the concept and/or make a pattern, in
this case a small plate inspired Mondrian's "Composition
Step 2 – Cut the glass – in this case 14 pieces, a 6"
base piece and 13 "puzzle" pieces to place on top.
Step 3 – Clean glass, glue up the pieces, allow to dry
thoroughly to prevent large bubbles.
Step 4 – Full fuse to 1480° F., up to 16+ hours,
resulting in completely integrated piece with rounded edges.
Step 5 – Slump into mold at 1280° F., up to 12+hours.
In this case a bisque ceramic mold was used to produce this
softly sloped appetizer or dessert plate.
For more information, email