Glassblowing

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Sculpting hot blown glas, glowing due to blackbody radiation.

Glassblowing is the process of forming glass into useful shapes while the glass is in a molten, semi-liquid state. A person who blows glass is called a glassblower, glasssmith, or gaffer.

1 History
2 Process
3 See also
4 External links

[edit] History

While the first evidence of man-made glass occurs in Mesopotamia in the Late-Third/Early-Second Millennium B.C., the actual "blowing" of glass using a tube did not occur until sometime in the First century BC in Roman Syria. Glassblowing is a form of art that requires exreme training and an intense level of aptitude. This advancement transformed the material's usefulness from a time-consuming process in which the medium was hot-formed around rough cores of mud and dung into a mass-producible material which could be quickly inflated into large, transparent, and leakproof vessels. Glassblowing techniques spread throughout the Roman world. Venice, particularly the island of Murano, became a centre for high quality glass manufacture in the late medieval period.

The relatively recent "studio glass movement" began in 1962 when Harvey Littleton, a ceramics professor, and Dominick Labino, a chemist and engineer, held two workshops at the Toledo Museum of Art, during which they began experimenting with melting glass in a small furnace and creating blown glass art. Thus Littleton and Labino are credited with being the first to make molten glass available to artists working in private studios. This approach to glassblowing blossomed into a worldwide movement, producing such flamboyant and prolific artists as Dale Chihuly, Dante Marioni, Fritz Driesbach and Marvin Lipofsky. Lino Tagliapietra was the first Murano-trained artist to leave and spread his knowledge in the United States. In 1971, Dale Chihuly began the Pilchuck Glass School near Stanwood, Washington. The Pilchuck School of Glass became the source of a great deal of the current American Studio Glass movement, and continues as such today.

In addition to glassblowing as an art, many individuals pursue glassblowing as a hobby. In fact, it is one of the fastest growing hobbies in North America.

[edit] Process

Reheating a piece

Traditionally, the glass was melted in furnaces from the raw ingredients of sand, limestone, soda ash, potash and other compounds. The transformation of raw materials into glass takes place well above 2000°F (1100°C); the glass turns into a burnt orange color, the glass is then left to "fine out" (allowing the bubbles to rise out of the mass), and then the working temperature is reduced in the furnace to around 2000°F (1100°C). "Soda-lime" glass remains somewhat plastic and workable, however, as low as 1000°F (550°C).

Glassblowing involves three furnaces. The first, which contains a crucible of molten glass, is simply referred to as "the furnace." The second is called the "Glory Hole", and is used to reheat a piece in between steps of working with it. The final furnace is called the "lehr" or "annealer", and is used to slowly cool the glass, over a period of a few hours to a few days, depending on the size of the pieces. This keeps the glass from cracking due to thermal stress. Historically, all three furnaces were contained in one, with a set of progressively cooler chamber for each of the three purposes. Many glassblowing studios in Mexico and South America still employ this method.

Items for sale from the glass lab at the Massachusetts Institute of Technology

The major tools involved are the blowpipe, the punty (or pontil), bench, marver, blocks, jacks, paddles, tweezers, and a variety of shears. The tip of the blowpipe is first preheated; then dipped in the molten glass in the furnace. The molten glass is 'gathered' on to the blowpipe in much the same way that honey is picked up on a dipper.

Glass created from complex murrine and zanfirico cane can possess a great deal of detail.

Then, this glass is rolled on the marver, which was traditionally a flat slab of marble, but today is more commonly a fairly thick flat sheet of steel. This forms a cool skin on the exterior of the molten glass and shapes it. Then air is blown into the pipe, creating a bubble. Then, one can gather over that bubble to create a larger piece. Blocks are ladle-like tools made from water-soaked fruit wood and are used similarly to the marver to shape and cool a piece in the early steps of creation. The bench is a glassblower's workstation, and has a place for the glassblower to sit, a place for the handheld tools, and two rails that the pipe or punty rides on while the blower works with the piece. Jacks are a tool shaped somewhat like large tweezers with two blades. Jacks are used for forming shape later in the creation of a piece. Paddles are flat pieces of wood or graphite used for creating flat spots like a bottom. Tweezers are used to pick out details or to pull on the glass. There are two important types of shears, straight shears and diamond shears. Straight shears are essentially bulky scissors, used for making linear cuts. Diamond shears have blades that form a diamond shape when partially open. These are used for cutting off masses of glass. Once a piece has been blown to its approximate final size, the bottom is finalized. Then, the piece is transferred to a punty, and the top is finalized. The entire process of a basic wine glass can be seen here and a simple striped bowl here. There are many ways to apply patterns and color to blown glass, including rolling molten glass in powdered color or larger pieces of colored glass called frit. Complex patterns with great detail can be created through the use of cane (rods of colored glass) and murrine (rods cut in cross-sections to reveal patterns). These pieces of color can be arranged in a pattern and 'picked up' by rolling a bubble of molten glass over them. An overview of how a piece is made from mixed cane and murrine is shown here. One of the most exacting and complicated caneworking techniques is 'reticello', which involves creating two bubbles from cane, each twisted in a different direction and then combining them and blowing out the final form. View a step-by-step reticello demonstration.

Lampworked glass beads and pendants

A lampworker, usually operating on a much smaller scale, historically used alcohol lamps and breath or bellows-driven air to create a hot flame at a workbench to manipulate preformed glass rods and tubes. These stock materials took form as laboratory glass, beads, and durable scientific "specimens" — miniature glass sculpture. The craft, which was raised to an art form in the late 1960's by Hans Godo Frabel (later followed by lampwork artists such as Milon Townsend and Robert Mickelson), is still practised today. The modern lampworker uses a flame of oxygen and propane or natural gas. The modern torch permits working both the soft glass from the furnace worker and the borosilicate glass (low-expansion) of the scientific glassblower who may have multiple headed torches and special lathes to help form the glass or fused quartz used for special projects. The molten glass is attached to a stainless steel or iron rod called a punty (or a punty rod, a pontil, or a mandrel) for shaping and transferring a hollow piece from the blowpipe for an opening to create from.