The past 25 to 30 years has seen a rebirth of glass as an art material. Today we are seeing tremendous exploration in the realm of glass, as artists and craftsmen push themselves and experiment with the potential of glass. As a medium for artistic expression, glass is used as a construction material, it is used as a surface to paint and to engrave, it is cut and blown, it is fused and slumped. Kiln-formed glass is that which is altered, fused, shaped, or textured by the extreme heat of a kiln.

In this article we focus on two kiln-formed techniques:

fusing, which is the heat bonding of glass, and

slumping, the procedure in which glass heated in a kiln conforms to the shape of a mold.

We followed Emily Brock as she created this vignette, a miniature stage-set in glass called "Oasis." The fusing process begins with flat sheets of colored glass which have been tested for compatibility--the glasses to be used in a finished work must have similar coefficients of expansion so they will not crack while cooling. When compatibility has been determined, shapes to be fused are cut from the glass sheets. Two layers of glass are laid together; when fused, the double layer of glass will form thick, soft, rounded edges. The base layer and top layer may be pieced into a design, for example, a checkerboard floor; the design may also be formed by laying a pattern of individual pieces on top of the double layer of glass.

The cut pieces of glass are put on a kiln shelf, on which a fresh coat of kiln wash has been applied. In the kiln, the glass is fired to approximately 1500 degrees Fahrenheit, or until full fuse, when the layers of glass are melted together and form one piece of glass. Next follows the critical annealing process during which the glass is cooled slowly to allow the entire thickness of glass to even out in temperature, thus relieving internal stresses in the glass.

If a curved shape is desired, such as a plate or bowl, a mold of ceramic, steel or other material that will not bend, warp, deform or explode at high temperatures is used.

The glass is placed on the molds, put into the kiln and fired to about 1200 degrees Fahrenheit, where heat and gravity allow the softened glass to conform, or slump, to the mold. During the fusing and slumping, it's actually necessary for Emily to look into the hot kiln in order to determine the moment the desired result occurs. Protective clothing, gloves and glasses are essential even when using kilns that have peep holes.

Emily's glass environments frequently contain unusual shapes such as folded napkins, newspapers or delicate long rods. Such shapes are created using techniques and equipment from the tradition of glass blowing. A glassblower's glory hole is a high-temperature chamber, in this case about 2150 degrees Fahrenheit, used for reshaping glass. To make sculptural pieces or long-rod shapes, Emily begins with squares of glass which are manipulated in the glory hole until soft enough to be pulled by two people into the desired shape. These, too, must be annealed after being formed.

At various times in the process, some of the components are sawed, ground, and polished to insure that they will fit together and have a finely detailed finish. The glass equipment such as saws, grinders, and polishers is always water-cooled. The final step is the assembly, for which Emily uses a silicone adhesive to join the numerous pieces.

Thanks to Emily and Terry Brock for their help and these photographs

Originally appeared in
The Collector’s Guide to the Albuquerque Metro Area - Volume 4