The J. Paul Getty Museum
- Glassmaking: history and techniques
- Ancient glass at the Getty
- Glassmaking technique: mold-blown glass
- Roman mold-blown glass
- Glassmaking technique: core-formed glass
- Glassmaking technique: free-blown glass
- Glassmaking technique: mosaic glass
- Glassmaking technique: gold glass
- Glassmaking technique: cameo glass
- Glassmaking quiz
Glassmaking: history and techniques
Cup with Blue, WHite, and Yellow Canes, Greek, 100-1 B.C.E., 1 1/2" x 4 1/16" diameter, (The J. Paul Getty Museum)
Glass is magical stuff. When you look at a glass object, you might never guess that it was once a hot, flowing liquid that could be inflated or molded or swirled into almost any shape.
According to the Getty's Art and Architecture Thesaurus, glass is:
an amorphous, inorganic substance made by fusing silica (silicon dioxide) with a basic oxide; generally transparent but often translucent or opaque. Its characteristic properties are its hardness and rigidity at ordinary temperatures, its capacity for plastic working at elevated temperatures, and its resistance to weathering and to most chemicals except hydrofluoric acid. Used for both utilitarian and decorative purposes, it can be formed into various shapes, colored or decorated. Glass originated as a glaze in Mesopotamia in about 3500 BCE and the first objects made wholly of glass date to about 2500 BC.
Glass had both practical and decorative uses in antiquity, just as it does today. The cup illlustrated above was used nearly 2,000 years ago for eating and drinking.
Blue Perfume Flask with a White Trail, Roman, A.D. 1–100, glass, 4 3/4 in. high (The J. Paul Getty Museum)
The ancient Greeks, Romans, and Etruscans stored ink, food, cosmetics, and perfumed oil in glass containers.
They used glass tableware and played with glass game pieces. They looked into glass mirrors, lit the night with glass lamps, and gazed through glass windows. The wealthy decorated their homes with glass mosaics, inlays, and statuettes.
Perfume was precious and merited fine containers such as this one. A glassmaker inflated this vessel and then wound a white trail around the blue glass body to create an elegant pattern.
White Perfume Flask with Purple Zigzags, Greek, 600–300 B.C.E., glass, 5 3/16 in. high (The J. Paul Getty Museum)
Core forming was one of the earliest glassmaking techniques. Glassmakers shaped the body of the vessel around a core of ceramic-like material, wound colored trails of hot glass around it, and added handles and a rim. They then let the vessel cool and removed the core. Most early core-formed containers were small flasks for perfumed oil, such as this one, which is only about five inches tall. The coloration of the container shown here indicates that it was meant to imitate marble.
Amber Bowl with White Ridges, Roman, 1–100 C.E., glass 4 1/16 in. diameter (The J. Paul Getty Museum)
Casting is a technique of pouring hot glass into a mold. After the glass cools, glassmakers use various grinding and cutting techniques to refine the vessel's form and decoration. Decorative patterns are sometimes cut into the sides with a cutting wheel.
Bowls were the most common cast vessels. Pendants, inlays, and other small objects were also created using this technique.
The bowl above has two layers of different colors. Much of the white overlayer was removed through grinding, leaving ridges of white over the amber underlayer.
Bowl with Blue and White Canes, Greek or Roman, 100–1 B.C.E., glass 2 1/16 inches high x 4 inches in diameter (The J. Paul Getty Museum)
Mosaic glass vessels are among the most colorful ancient containers. They were formed by fusing numerous slices or ribbons (lengths) of cane in molds until they melted together into a swirl of colors, as seen on this blue and white bowl.
Multicolored canes and figural compositions for plaques and beads were made by layering different colors and manipulating them into designs. Roman mosaic glass later inspired Venetian glassmakers to create millefiori (Italian for "thousand flowers").
This pyxis, a lidded cosmetics or jewelry box, is made from marbled glass, a variant of mosaic glass. The Roman glassmaker created a swirling pattern (similar to agate) by melting multiple colors of glass together
Lidded Container with Amber and White Marbling, Roman, A.D. 1–100 C.E. Roman, glass, 2 inches high x 2 1/4 inches in diameter
In the environs of Jerusalem, in about 50 B.C.E., glassmakers discovered they could inflate glass into a bubble at the end of a tube. This new glassblowing technique allowed glassmakers to produce vessels so quickly and cheaply that glass containers began to replace clay ones for household use.
Blue Splashware Cup, Roman, 1–100 C.E, glass, 4 13/16 inches high x 5 11/16 inches in diameter (The J. Paul Getty Museum)
Blown-glass vessels were decorated using a variety of techniques—pinching, pressing, pulling, painting, applying trails (threads of glass), and rolling in colored glass chips before reinflating (to create splashware). Glass with cut decoration was made to imitate hard-to-cut rock crystal and is often colorless. Painted glass is very rare, and the pigment has often worn away.
The splashware cup above was a luxury item that was probably used in a wealthy home. It was decorated by rolling hot blue glass into glass chips of other colors.
In about 25 B.C.E. glassmakers began to create decorative vessels, such as this cup, by blowing glass into a mold with incised designs. Mold fragments of stone, clay, bronze, and plaster have survived from antiquity. The earliest makers of molds for glassware may have been ceramists familiar with constructing molds for clay vessels.
Lotus Bud Beaker, Roman, Eastern Mediterranean, 1st century C.E., mold-blown glass, 8 3/8 inches (The J. Paul Getty Museum)
Mold designs often incorporated decorative elements, such as palm fronds, columns, or lotus buds (as on this vessel), that disguise the joins of different sections.
Glassmakers decorate vessels using a variety of tools and techniques. They use pincers and tongs to pinch, pull, and push hot glass into different shapes and patterns. They wind glass around a vessel to create snakelike patterns and add handles, rims, and feet.
To create a special kind of decorative glass known as splashware, glassmakers roll a vessel in multicolored glass chips, reheat the vessel, and then further inflate it to stretch the chips across the surface to look like splashes of color.
Glassmakers also ornament glass vessels after they cool by painting them or using a lathe and cutting wheel to form decorative patterns. Painted glass vessels are rare, and none have survived with their pigments intact.
Want to join the conversation?
- "Painted glass is very rare, and the pigment has often worn away. " Is it possible for art curators to restore the original colors and/or original drawings to the glass, or does the paint disappear completely?(7 votes)
- UV light is often used to determine the pigments used on greek statues (which wore away), and I'm only guessing the same method could be used on the glass. You can read an article about this use of UV light here: http://harvardmagazine.com/2007/11/dazzlers-html(3 votes)
- Many times throughout this essay the writer refers to something called "cane" such as in this sentence... "They were formed by fusing numerous slices or ribbons (lengths) of cane in molds until they melted together into a swirl of colors, as seen on this blue and white bowl."
What is "cane" exactly?(4 votes)
- Cane refers to rods of glass with color; and these rods can be simple, containing a single color, or they can be complex and contain many strands of multiple colors in pattern.(4 votes)
- Can all glass be remelted and reformed?(4 votes)
- Yes and no. While you can melt most glass, a lot of glass is not compatible with other glass. For example, your average jam jar or applesauce container is not compatible with your average wine bottle even if they seem to be the same color. It has to do with the COE or Coefficient of Expansion.(1 vote)
- Is core forming process still used in glassmaking?(3 votes)
- Bulletproof glass is made from which material please explain in a vedeo mode .(2 votes)
- Is glass made of hot melted sand too?(2 votes)
- colured glass is made by amounts of metal oxides?(1 vote)
- I'm writing a science fiction novel in which I have a civilization substitute glass for metal. Is that possible? Wagon wheels of glass? Weapons? The civilization is pre-industrial age. No gas combustion. Primitive but not too primitive.(1 vote)
- sure, if you make assumptions about the properties of glass, present them to the reader, and remain consistent.(1 vote)