A Brief History of Glassblowing
In prehistoric times, obsidian, a natural glass formed by volcanic eruptions, was prized for its hardness by primitive man and was used to make tools and arrowheads. Man-made glass amulets and beads from as far back as 4000 BC have been discovered by archaeologists. Around this period, the basic formula for glass was discovered – sand, plant ash to help melting and lime to stabilize the glass and protect it from moisture. Around 1500 BC in Mesopotamia and Egypt the first glass vessels were created by shaping hot glass around solid cores of earth and dung. After the glass cooled the earthen plug was removed and discarded, leaving a hollow form. The techniques for making these early glass vessels were a closely guarded secret and glass vessels were owned only by royalty and the very wealthy. The earliest glass tile mosaics were made during this period from thin slices of colored glass rods inlaid upon walls, wooden boxes and ceramic vessels.
The Roman Empire
The Syrians invented the blowpipe around 300 BC and the foundation of modern glassblowing was laid. The Roman Empire embraced these new techniques for making glass vessels and experimentation with a wide variety of new shapes and forms began. Molds were developed in conjunction with the blowing techniques to make shapes and patterns on the glass. New formulas for color were invented and gold and silver inlays were used to decorate vessels. The first enameling techniques came about during this period and were perfected in Egypt and the Middle East. The production of glass became more affordable and widespread. Glass from the Roman era is sufficiently plentiful that modern collectors can fairly easily afford to obtain small vessels of this period. During the Dark Ages, most of the glassblowing knowledge in Europe was lost, leaving the more civilized Middle East to carry on the glass art tradition.
The Middle Ages
During the middle ages, Venice, Italy became the center of glassmaking as a result of learning the secrets of glassblowing through trade with the Middle East. In order to maintain their virtual trade monopoly on glass, the government forced all the glassblowers in Venice to move to the island of Murano in 1291. Further perfecting their craft while in exile, the Murano glassblowers developed an incredibly clear glass called cristalo, along with new vivid colors such as deep blue, amethyst and emerald. Despite the fact that leaving the island was punishable by death, many Venetian glassblowers did manage to escape Murano and spread their new techniques and new colors throughout Europe and parts of Asia.
During the Renaissance, glassblowing techniques spread and developed throughout Europe. In the 17th century, the first widely available textbook on glassblowing, "L'Arte Vetraria (The Art of Glass)" was published in Italy. Window glass, glass bottles and glass drinking vessels became even more common and available to the average person. New glass technology, such as leaded glass and diamond engraving became widespread.
Glass came to the American colonies in 1607 with the Jamestown settlers. Most decorative glass was still imported from Europe during the colonial period with American glassmakers producing primarily windows and bottles. The invention of mechanical presses in the late 1800s made functional glass production faster and easier throughout the world. By the end of the 19th century, even people of very modest means had glass bottles, jars, glasses, butter dishes and flower vases in their homes.
Art Nouveau Period
The late 1800s saw the marriage of art and production with artists such as Emile Galle, Eugene Rousseau and the famous Louis Comfort Tiffany working with the large glass houses designing lamps, vessels, windows and art pieces from blown and stained glass.
The 1960s to Today
The 1960s ushered in the rise of the studio glass movement in America. Individual artists, like Harvey Littleton, began opening their own glassblowing studios independently of the large glass factories to pursue their own artistic visions and to develop new techniques for glass blowing, casting and carving. The movement began in America and spread across the globe. Museums began to look at glass art seriously and glass specific museums such as the Corning Museum of Glass in New York were established. The Pacific Northwest became a well known hub of studio glass art, being home to the famous Pilchuck Studio and the new Museum of Glass Art in Tacoma.
Pre-historic Obsidian Arrowheads
Old Map of Venice, Italy and the Island of Murano.
19th Century Blown Glass Trade Card.
Founder of the Studio Glass Movement, Harvey Littleton.
Glossary of Basic Glassblowing Terms
Cullet: Beads of raw, clear glass used in furnaces for glassblowing.
Soft Glass: A term for the type of glass used in the glassblowing process that is malleable but easily breakable when hardened.
Borosilicate Glass: Also known as Pyrex, this is the type of glass you will find in
kitchenware. Workable at a higher temperature than soft glass, borosilicate glass is
stronger and can withstand rougher handling than typical soft glass.
Furnace: The heat source for glassblowing and source for the molten glass used in
blowing. Glassblowing furnaces are typically gas-powered and are heated to 2,000
degrees Fahrenheit (1,100 degrees Centigrade.)
Gloryhole: Heated barrel in which molten glass is reheated for shaping.
Blowpipe: Hollow metal pipe used to blow air into hot glass.
Yoke: Stand which supports blowpipes while the glass is being reheated in the gloryhole.
Gather: The process of placing molten glass onto the end of a blowpipe – the end of the pipe is placed into the mass of furnace glass and twirled. The process of gathering is similar to using a dipper to take honey from a jar. Gather also is the name for the actual mass of glass on the end of the pipe at the beginning of the blowing process.
Punty: Solid metal rod applied to the bottom of a blown glass piece for further shaping and work on the lip of the vessel.
Gaffer: The technician who is doing the main work of shaping and transferring glass during the glassblowing process. The gaffer has at least one assistant to help in the process of moving the glass from pipe to punty and to shape and properly heat and cool the glass.
Marver: Metal table used to add color and aid in shaping hot glass on a pipe. In the old days, marvers were made of marble slabs, hence their name.
Bench: Glassblower’s work station – arms of the bench act as supports for rolling the blowpipe.
Block: Large wooden spoon-shaped tool for shaping glass.
Paddles: Wooden tools used to flatten the bottoms of pieces and protect the glassblowers from the heat of the furnace.
Optic Mold: Metal mold with various notches cut into the mold to put a ridged pattern into the glass or separate the color in the glass into lines.
Jacks: A very important glassblowing tool with two long metal blades secured at the top by a u-shaped miniature marver called a “heel.” Jacks, which resemble a large pair of tweezers, come in a variety of sizes and have many uses including shaping, opening pieces and adding in a jack line.
Jack Line: Constricted area made in hot glass between the glass and the head of a pipe using the jacks. This helps to separate the piece from the pipe.
Annealer: Oven used to slowly cool and harden glass after it has been shaped through
the glassblowing process. Glass must cool slowly or it will crack and break.
Glass Color: Glass coloring comes in several forms and is added to the piece in progress in a variety of ways. Soft glass color is manufactured by only four major companies in the world – one in New Zealand and three in Germany. All the color used at Seattle Glassblowing Studio is made by Kugler Color in Bavaria, Germany, from chemical formulas kept in the Kugler family for generations.
Bar Color: Glass color in the form of hard bars of solid color which can be cut into the size needed for the project. Clear glass is infused with metals, chemicals and minerals to produce various colors and effects.
Overlay: The process of dropping the heating color bar onto a bubble of clear glass.
Frit: Glass color in powdered or ground form. Frit can range in size from fine powder like talc to pieces the size of gravel. The different sizes give different color effects from all over coverage to a mottled, dappled effect. Hot glass is rolled through the frit which is laid out on the marver. Since the frit is also made of glass, the heat of the molten glass piece melts the color into the vessel.
Cane: Glass bar that is heated and stretched the length of the room to create thin strips of color.
Dichroic Glass: Glass that appears to be different colors when light is shone through it vs. when light reflects against it. It is applied to sheet glass as a vapor. Decals can be made in a variety of designs with this process and then embedded in clear glass.
Leaf/Foil: Thin metal foil that can be applied to the exterior of glass. Silver, gold and copper are common foil colors.