River Market ArtSpace

How'd They Do That? -- Glass

The fundamentals of glass making have changed little since their beginnings. In fact, an Egyptian glassworker of the 14th century B.C. would easily recognize today's basic tools and processes. Glassworkers routinely gather molten (melted) glass on metal pipes or rods and shape it using various wood and metal tools and/or by blowing into the pipes to expand the glass. The skillful combination of gravity, centrifugal force, and lung power allows the artist to shape the piece with subtle gestures, or by dramatically spinning and twirling it.

Some of today's artists also use computers to regulate temperatures during the melting and annealing (hardening) steps. Diamond coated wheels are used to cut and polish the pieces to a high luster.

Glass Facts

Blown Glass, or Free Blown Glass is shaped by air pressure, usually mouth-blowing through a metal tube (pipe) that molten glass has been attached to. The glass is manipulated simultaneously with hand-tools, paddles, molds, etc.

Cased Glass is glass completely covered by added layers through dipping or other techniques. Outer layers can be cut away to reveal layers of color or transparency beneath.

Etched Glass is decorated by the use of hydrofluoric acid. A resist-wax can be applied to the surface and the pattern drawn through the wax. The exposed glass is etched by the acid.

Graal Technique is hot glass made with a color overlay that is cut, etched, or sandblasted with a decoration after cooling to room temperature. The piece is then brought up again to working temperature (2000 degrees Fahrenheit) for further working or shaping.

Hot Glass is glass worked in its molten state from the furnace, in 3 dimensions.

Sandblasted Glass is "frosted" by blowing abrasives under high pressure on to the surface. Patterns can be produced by masking sections. Masked sections can be either transparent or opaque.

Slumped Glass is heated and formed over molded forms.

Stained Glass is usually flat pieces of glass cut to patterns and soldered together to form windows or panels.

Surface Decoration – Colored glass or chemicals can be applied to hot glass during the blowing process, often by rolling it over a bed of powdered glass, silver nitrate, gold leaf, or fuming with acid solutions.