All About Glass

All About Glass

This is your resource for exploring various topics in glass: delve deeper with this collection of articles, multimedia, and virtual books all about glass. Content is frequently added to the area, so check back for new items. If you have a topic you'd like to see covered, send us your suggestion. If you have a specific question, Ask a Glass Question at our Rakow Research Library.

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Raw Materials of Glass
Video

See and understand the magical process of making glass from simple materials, by using great heat. Until the most recent times, glassmaking was a closely guarded secret passed on within workshops or even families from one generation to the next, often over hundreds of years.

Prince Rupert's Drop
Video

Don't try this at home! A classic demonstration involving exploding glass: it spectacularly shows both the great strength and vulnerability of glass that has been rapidly cooled from the molten state.

Optic Molding
Video

This technique was invented by Roman glassworkers. It was indispensable in glasshouses of the Middle Ages and flourished in Venice. Also known as dip molding, it remains popular today.

Murrine Use
Video

Once murrine canes are cut into thin slices, they can be fused and slumped, flameworked, or blown. Here, murrine canes are used in demonstrations of a Roman period process and a Renaissance Venetian process.

Ladle Casting
Video

Molten glass can be cast by a method virtually identical to that used for casting metal. Here, molten glass at 2300 degrees Fahrenheit is ladled into a mold made of sand. The process is relatively easy as hot glassworking processes go...but hot!

Cutting Glass
Video

Cutting thin sheet glass is almost as easy as it looks in this video clip...but not quite! Curves really are much trickier than straight lines. The process shown would have been completely familiar to medieval window glaziers.

Flameworked Beads
Video

Flameworking (sometimes called "lampworking") is the process of directing a flame onto a piece of glass in order to create form or decoration. Beads were likely among the first glass objects to be made by flameworking.

Chunk Casting
Video

Chunks of glass are placed in a mold, then heated in a kiln until the glass softens and flows downward to gradually fill the mold. Popular with contemporary artists, this method avoids the need for a giant melting furnace filled with molten glass.

Coloring Objects
Video

Five different methods of using colored glass are demonstrated; some produce a uniformly colored object, others a splotchy or mottled effect. Glass artists today use whatever method best suits their aesthetic choices.

Bowl with Roman Foot and Folded Edge
Video

Roman glassworkers, tirelessly creative and inventive, were fond of folding and manipulating inflated glass in a variety of ways for different purposes. Two of their characteristic structures—both functional and beautiful—are demonstrated.

Pâte de Verre
Video

This is another casting technique that—like glassblowing—only works with glass. Whereas glassblowing was invented about 50 BC, pâte de verre is a process invented in France in the 19th century. It allows subtle gradations of color, possible with no other glassworking process.

Flameworked Vessels
Video

Beginning in the 1800s, glassworkers used flameworking to make vessels considerably larger than previously possible. Bigger and more sophisticated torches allowed the increase in scale, while retaining the flameworker's ability to create minute details.

Cracking Off
Video

As if glassblowing wasn't fast enough—it takes under three minutes to make a Roman bottle—cracking-off made the process even faster. This technique was well known by AD 20 or so, and cut the manufacturing time of simple tumblers in half.

Cane Making
Video

While glass canes can be used alone, for example as stirring rods, usually they are incorporated in vessels or sculpture. An infinite variety of decoration is possible. Here we see two examples that are intended to be viewed from the side.

Building a Goblet on a Blowpipe
Video

Here is virtuoso Venetian-style glassblowing "without a net." One mistake and all is lost! Where "making a goblet from parts" allows mistakes to be isolated and destroyed, this process moves relentlessly forward, allowing no retakes.

Fusing and Slumping
Video

Popular among glass artists today, as it was in the golden age of Greece and the Roman Empire, this technique softens and shapes glass in a kiln. Various preparatory steps are shown in the making of a contemporary sculpture.

Learn About Glass Enameling
Video

It could have been so simple...but it wasn't! Until recent times (about 1800), permanent enamels had to be fired on glass vessels by an amazingly laborious process, shown here. Today, the process really is as easy as it looks.

Solder vs. Glass Rod
Video

See what really sets glass apart from metal and then begin to understand why humans have invented such odd ways of shaping it while hot: core-forming, fusing, slumping, and—oddest of all—glassblowing.

Glass Blowing
Video

Discover the history and process of glass blowing with experts at the Corning Museum of Glass.

Medieval Goblet
Video

Arguably the most beautiful medieval glass vessel to survive, this goblet is also original. It is probably the invention of one glassblower who took the secret of its manufacture to his grave. See this extraordinarily elegant process, not rediscovered until the 20th century.

Core Forming
Video

This was the common method of making small glass vessels from around 1500 BC until the discovery of glassblowing. Dung, clay, and glass came together in a seemingly odd process that was indispensable for more than a millennium and a half.

Flameworked Sculpture
Video

Artists have proven that glass as a medium for sculpture is virtually without limits. Among hot-working processes, flameworking allows the greatest detail and the smallest scale. Surprisingly though, it can also be used to create sculpture large enough to fill rooms.

Paperweights
Video

Encasing glass decorations and small-scale sculpture within a mass of molten colorless glass to make paperweights began in the 1840s. It continues to be practiced by a limited number of specialized glass artists.

Air Twist Stem
Video

A technique unique to glass, air twist requires very high quality material for success. When sparkling lead crystal became common in 18th-century England, the air twist technique spread rapidly.

Mold Blowing
Video

By about AD 20, Roman workers had discovered that a bubble of molten glass could be lowered into a mold and then further inflated to fill the mold. In this way, the full-size vessel, complete with elaborate decoration, was made almost instantly.

Annealing and Tension in Glass
Video

Hot-working processes used to form a glass object—glassblowing for example—must be followed by a very gradual cooling period called annealing. See what happens when an object is not properly annealed and learn why it breaks.

Murrine Making
Video

Alternately using different colored glasses, plunged into different shaped dip molds, to build up a variety of layers, a stout cane is drawn. When the cane is cut, the pattern is revealed at the cross-section.

Cameo Glass Blank
Video

Some of the first glassblowers working in Italy—perhaps as early as 30 BC—made blanks for craftspeople accustomed to decorating hardstone objects. The glassblowing process required two contrasting glasses, usually blue and white.

Engraving Lathe
Video

Essentially the same as lathe cutting, the engraving lathe is generally used for small-scale projects often involving the creation of extremely fine details, such as the eyelashes on a portrait.

Gold Leaf
Video

Gold decoration has been popular since Egyptian times. Roman, Byzantine, and Islamic workshops also used it frequently. Beginning in the Renaissance, gold decoration became an indispensable part of the Venetian style.

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