The typical home contains dozens of items made of glass, from canning jars in the pantry to decorative knickknacks on the mantel to the windows and doors that insulate our living spaces and filter light. Despite the surge of plastic products following World War II, this delicate translucent material has maintained its essential place in our homes and daily routines.
Historically, the glass items that we now take for granted were highly coveted luxuries, accessible for a time only to the rich and royal. The evolution of glassmaking has transformed the material from an exclusive work of art to an ubiquitous aspect of modern living. But when — and how — did humans first learn to make this valuable, versatile material?
What exactly is glass?
To understand how glass is made, we must first understand what glass is and how it’s different from other materials. Rather than a single, uniform substance, glass is an unusual state of matter that looks like a solid but acts like a liquid. The formation of glass occurs when a molten substance is cooled so rapidly that its atoms are unable to organize into the latticelike crystalline structure characteristic of a solid. Likewise, these atoms also lack the ability to move randomly, as they would in a liquid. Because of the unusual properties of its atoms, glass is in a distinctly unique category of its own, neither fully solid nor fully liquid, referred to as a rigid liquid or an amorphous solid.
While we typically think of glass as a human invention, it also occurs naturally. Lightning strikes, meteorite impacts, volcanic eruptions, and even some sea creatures can produce natural glasses that are similar in composition to human-made glass. Natural glass is formed when silica-rich sand or rocks are heated to high temperatures and rapidly cooled. Examples include obsidian, created by the rapid cooling of volcanic lava; tektites and impactites, formed by the impact of meteorites; fulgurites, created by lightning striking sand; and even the siliceous (silica) skeletons produced by certain types of sea sponges and algae.
Glassmaking is thousands of years old
Ancient glass was made from three primary ingredients: sand (silicon dioxide or silica), an alkali oxide (typically soda ash or natron), and lime. When combined and heated to 2,400-2,700 degrees Fahrenheit, the ingredients fused to form glass.
The earliest evidence of glassmaking includes objects such as beads, pendants, and inlaysthat were cast in open molds, but glass may have initially occurred as an accidental byproduct in the workshops of Bronze Age metalworkers and ceramicists. While archaeologists have found glass artifacts produced by the Egyptians and Phoenicians dating back to the second millennium BCE, current theory suggests that the first human-made glass dates back even further, to Mesopotamian craftsmen during the third millennium BCE, some 4,000 to 5,000 years ago.
The birthplace of glassmaking
Researchers have long debated the birthplace of glassmaking, in part because glass products, as well as the raw materials used for the glassmaking process, such as blocks of colored glass called ingots, were frequently exchanged along trade routes. But advances in archaeology and chemistry have helped researchers better pinpoint the origins of glassmaking to ancient Mesopotamia (modern-day Iraq).
Situated between the Tigris and Euphrates rivers, Mesopotamia was well suited for trading its glass materials and glassmaking knowledge. By the second millennium BCE, artisans had developed sophisticated techniques to shape glass and create vessels. One such method, called core forming, involved creating a hollow vessel by covering a mud core with glass and then removing the hardened mud. Core-formed objects have been found in Mesopotamia, as well as Egypt, where glassmaking also flourished.
Glass trading between Egypt and Assyria was mentioned in the Amarna Letters, a set of cuneiform clay tablets dating to the 14th century BCE that were excavated in the ancient desert city of Amarna, in modern-day Egypt. Not surprisingly, chemical analysis of glass excavated in Amarna found the glass was ofMesopotamian origin. Similarly, the presence of cobalt glass beads in Scandinavian Bronze Age tombs has provided evidence of a complex trading system linking Mesopotamia and Egypt with the Nordic Bronze Age cultures. These findings highlight the extensive trade networks of the ancient world, and demonstrate the far-reaching influence of Mesopotamian glassmaking, even as other cultures began to adapt and develop their own glassmaking methods.
Beads Found in 3,400-year-old Nordic Graves Were Made by King Tut's Glassmaker
Stunning glass beads found in Danish Bronze Age burials dating to 3400 years ago turn out to have come from ancient Egypt – in fact, from the workshop that made the blue beads buried with the famous boy-king Tutankhamun. The discovery proves that there were established trade routes between the far north and Levant as early as the 13th century BCE.
Twenty-three of the glass beads found in Danish Bronze Age burials by the team of Danish and French archaeologists were blue, a rare color in ancient times.
“Lapis lazuli was the most precious gemstone in Nordic Late Bronze Age. Blue glass was the next best thing," Jeanette Varberg, who is associated with the research, told Haaretz. "In the north it must have been almost magic. A piece of heaven." (Lapis lazuli is a deep blue semi-precious gemstone.)
“Lapis lazuli was the most precious gemstone in Nordic Late Bronze Age. Blue glass was the next best thing," Jeanette Varberg, who is associated with the research, told Haaretz. "In the north it must have been almost magic. A piece of heaven." (Lapis lazuli is a deep blue semi-precious gemstone.)
One of the blue glass beads was found with a Bronze Age woman buried in Olby, Denmark, in a hollowed oak coffin wearing a sun disc, a smart string skirt decorated with tinkling, small bronze tubes (a decoration on the cords, placed at the front of the skirt), and an overarm bracelet made of amber beads. She had evidently been quite well to do.
Another blue bead was found in a necklace together with four pieces of amber, in the burial of another woman.
The 23 blue glass beads were analyzed using plasma-spectrometry, a technique that enables comparison of trace elements in the beads without destroying them.
The analysis showed that the blue beads buried with the women turned out to have originated from the same glass workshop in Amarna that adorned King Tutankhamun at his funeral in 1323 BCE. King Tuts golden deathmask contains stripes of blue glass in the headdress, as well as in the inlay of his false beard.
Glass beads were a luxury adornment in ancient Egypt. They were not especially prevalent, except in the graves of the elite where the selection was choice but limited in quantity. It may seem inexplicable how cobalt beads fit for kings could end up in Nordic burials. But Kaul Flemming and Jeanette Varberg speculate that the two ancient lands traded the luxury glass beads for amber.
Denmark is rich in amber and it was the primary exchange item from the North,” said Varberg.
Nordic amber in Mycenae
The Egyptian and Mesopotamian glass beads found in the graves in Denmark indicates that trade was established already 3000 years ago, and conversely, Nordic amber has been found as far south as in Mycenae, Greece and at Qatna, near Homs in Syria.
Together with other finds such as Cypriot copper found in Sweden, the picture of an elaborate trade system emerges. Also, Nordic amber beads as well as beads made of Egyptian glass and copper ingots formed part of the precious cargo of the ship wrecked at Uluburun, outside the coast of Turkey.
“The glass beads travelled along the same roads as the amber. The glass came from Mesopotamia and Egypt to the North while the amber came from the north and reached the most distant part of the Mediterranean and even beyond,” Kaul Flemming told Haaretz.
However the glass exchange almost stops around 1177 BCE - probably due to attacks by the Sea Peoples.
Trade systems in the Eastern Mediterranean seem to have collapsed around 1200 BC, which must have been due to troubled times, perhaps war and strife, and the emergence of the Sea Peoples. This collapse can also be observed in the Nordic burials. Fewer glass beads seem to have reached the north,” said Flemming, and adds, “However an interesting phenomena occurred at the same time in Italy. In the Po Valley, new workshops arose, where they turned glass into glass beads. There are also large workshops where they processed Nordic amber from natural lumps into finished gems.”
Sun Worship a Global Matter
The Danish researchers believe the blue glass beads deposited in the graves had religious significance. Also, glass and amber seem to be closely linked, in the North as well as in the South. “The glass and amber beads were found closely together, part of the same piece of ornament, as a part of a necklace or at the left arm,” says Flemming.
The juxtaposition of the glass and amber was not coincidence, the archaeologists believe. Particular social values would have been conveyed by wearing the two substances together: it was people at the highest levels of society who controlled the collection and distribution of amber, benefited from its export, and who were the receivers of the valuable and exotic glass beads.
The juxtaposition of the glass and amber was not coincidence, the archaeologists believe. Particular social values would have been conveyed by wearing the two substances together: it was people at the highest levels of society who controlled the collection and distribution of amber, benefited from its export, and who were the receivers of the valuable and exotic glass beads.
If we allow ourselves to consider such mythological and connected magical properties of glass and amber in the Bronze Age North, then it should not be difficult to recognize the magical values of these materials being enhanced when carried closely together, says Flemming and adds, “In a mysterious way, the color of amber and the color of the glass might have – when working together – provided a sort of a narrative of the myth related to the eternal voyage of the sun: In the heavens, in underworld depths of the waters including the sea.”
“The sun cult in the Nordic bronze age has resemblance to the Egyptian religion," concludes Varberg. "And yes, I see clear evidence of ideas travelling along the same exchange routes as amber and glass."
Imported glass beads from Egypt and Mesopotamia have also been found in Israel. Roni Hoofien at Tel Aviv University is constructing a new typological system and tracing manufacturing techniques and raw material provenance using the beads assemblage of Tel-Azekah, in the Judean Shepelah. “Because of the close proximity of Tel Azekah to Egypt, we believe that the glass beads were imported from Egypt," she said.