AN INTRO TO GLASS: Glass is an inorganic material that is neither solid nor liquid but has attributes of both states, that is, it has the random, disordered structure of a liquid and the rigidity of a crystalline sold. The main ingredient in glass is sand or silica, mixed with soda ash, potash, lead or lime and other components that have been fused together at very high temperatures. COLOUR is the result of the addition of metals such as cobalt, nickel, copper and iron while the glass is in the raw batch state. Colour can be opaque or transparent. There are several different types of glass used in the creation of glass art objects. SODA GLASS: Composed of sand, soda and calcium carbonate, soda glass forms a: hard glass which must be worked quickly while hot. Since it becomes hard very fast as it cools, frequent reheating is required as the shape is being formed. LEAD GLASS: Lead glass is composed of sand and lead. It's composition makes it a softer glass than soda glass and therefore, it carves more easily since it stays soft for a longer time during the cooling process. CRYSTAL: This is a descriptive term meaning "clear". Sometimes it is loosely used to describe lead glass. FORMING METHODS: The glass is formed using a number of different methods. Most important among these methods are the various HOT GLASS techniques: FREE-BLOWN GLASS: This is the process of forming glass without use of a mould. The glass is "free-blown" in the air from the MELT or molten glass in the furnace. This method results in unique, one-of-a-kind objects. HANDBLOWN GLASS: Objects are formed by blowing hot glass into a mould. CAST GLASS: A glass object that has been formed by pouring molten glass into a mould. Other glass forming methods include FUSED GLASS, SLUMPED GLASS and PRESSED GLASS. Additionally, glass may be manipulated while cold. COLD GLASS: May be sculpted, carved, drilled, cut, sanded, etched, etc. FREE-BLOWN GLASS MAKING: Glass is made by melting together the raw ingredients in a furnace or TANK at 2200-2300° F. On the side of the tank is an opening or GLORY HOLE through which a glassblower can gather a gob or collar, often called a GATHER, of molten glass on the end of a BLOWPIPE, a hollow stainless steel or iron tube to six feet long used to blow air into the glass in order to achieve the desired shape. TEMPERATURE AND TIMING ARE EVERYTHING IN GLASS BLOWING: While it is being shaped, the glass must be kept hot so that it will be soft enough to work. To do this the glass blower returns the glass to glory hole frequently throughout the shaping process. After some initial shaping of the object, the first blow through the blowpipe occurs. The blowing takes just seconds. Most of the shaping is done by hand. If desired, the blower picks up colour and continues to shape the piece. Colour, available crushed or in rods, can be added directly to the glass in its raw batch state in the tank and picked up on the gather; or it can be placed on the MARVER, a steel table on which the hot glass is rolled and shaped, and the molten glass can be rolled in it. The piece is built up in layers. The rod is turned constantly to maintain shape. Wood blocks are also used to hold and shape the glass while it is being worked. As the object cools, it no longer drips but stiffens and other tools and techniques are used to shape it. The most essential tool is a steel JACK, resembling a large pair of springed tweezers, is used to diminish the diameter of the blown body, or elongate and shape parts such as stems. The jack's importance is apparent from the blower's name for it - it is called, simply, THE TOOL. As well, the glass piece on the rod can be held down and its own weight will change its shape, or the rod can be swung around in the air, which will alter the shape. Once the piece is shaped, a solid iron rod called a PUNTEE or PONTIL is used to take the expanded object off the blowpipe so that the top can be finished. This is done by taking a small gather of glass on the puntee to attach to the bottom of the object, which can then be "CRACKED OFF" the blowpipe. NECKING, which reduced the thickness of the break-off point, is achieved by rotating the neck of the piece between the arms of the TONGS. The lip of the piece can then be trimmed with SHEARS while it is hot. Lastly, the piece is rotated to flip up the lip and produce a smooth finish. When cooled and solidified, the piece is knocked off the pintail leaving the PUNTEE or PONTIL MARK on the bottom. This mark is the indicator of blown glass. The object then goes into an ANNEALING OVEN to cool down completely. Glass must be cooled very slowly or it will crack. This gradual cooling toughens the glass and eliminates internal stress. When the object is completely cooled, designs can be added to its surface using a number of methods. GLASS CUTTING, INTAGLIO CUTTING and ENGRAVING are all processes which employ a cutting wheel. ACID ETCHING involves covering the glass with an acid-resistant protective layer, scratching on a design and then applying hydrofluoric acid to etch the pattern into the glass. Etching by SAND BLASTING abrades the surface of the glass. Glues or tapes can be put on the piece to create drawings. The design is then etched by sand blasting the exposed surfaces. Finally the object is polished using a cork or felt wheel. Suggested further reading: Cooke, Frederick, Glass - Twentieth Century Design, New York: Beil & Hyman Ltd. Flavell, Ray and Claude Smale, Studio Glassmaking*, New York: Van Nostrand Reinhoid Phillips, Phoebe, Ed., The Encyclopaedia of Glass*, New York: Spring Books These books are available in the Canadian Clay & Glass Gallery Library and Resource Centre. The Library and Resource Centre is available by appointment only. To arrange an appointment, please contact the Administrative Assistant at the Canadian Clay & Glass Gallery.