Aarhus University researchers discovered that ancient craftspeople in the early Viking Age, around the year 700, employed innovative and sustainable methods when they gave old Roman glass mosaics new life as glass beads.
The study revealed new developments and intriguing insights about Viking bead makers that were previously unknown.
Northern Europe showed a booming industry of glass bead production in the early Middle Ages. Ribe was an important trading town during the Viking Age. At the beginning of the eighth century, a trading post was built on the north side of the river Ribe, to which traders and craftsmen flocked from all over to manufacture and sell products such as brooches, suit buckles, combs, and colored glass beads.
When glass became scarce in the Early Middle Ages, coloured glass cubes, known as tesserae, were torn from mosaics in abandoned Roman and Byzantine temples, palaces, and baths, transported North, and traded at emporia towns such as Ribe, where beadmakers melted them down in large vessels and shaped them into beads.
Until previously, archaeologists assumed that the opaque white tesserae were utilized as raw material by pearl makers to create white, opaque beads.
Smart and sustainable production
And it is here that an Aarhus University geochemist and archaeologist, along with a museum curator from Ribe have made a surprising discovery:
The chemical composition of white Viking beads from one of the first workshops revealed that the glassmakers had discovered a more sustainable way to save time and wood for their furnaces: crush gold-gilded, transparent glass cubes, remelt them at low temperature, stir to trap air in the form of bubbles, wrap the glass around an iron mandrel to form beads, and voila! — opaque white beads created in a short time using a minimum of resources.
The valuable ultra-thin sheets of gold stuck to the surface of the gold mosaic stone were of course salvaged by the glassmaker prior to remelting the glass, but the new findings show that some gold inevitably had ended up in the melting pot. The researchers demonstrate that the gold mosaic stones were the raw material for the beads by using tiny drips of gold in the white beads, numerous air holes (which is why the beads are opaque), and the lack of chemical color tracers.
Such traces of gold were discovered not just in the white but also in the blue beads from the same workshop. Here the chemistry shows that the glassmaker’s recipe consisted of a mixture of the blue and golden mosaic stones. Mixing them was necessary because the Roman blue mosaic stones contained high concentrations of chemical substances which made them opaque — and therefore ideal for mosaics, but not for blue beads. By thus diluting the chemical substances, the result was the deep blue, transparent glass that we know from Viking Age beads.
Connoisseur craftsmanship
Instead, the bead maker in Ribe may have chosen to dilute the glass mixture with old shards from funnel beakers found in the workshop. But these turned out to be old, contaminated, Roman glass that had been remelted over and over again.
“And the glassmakers in Ribe were clearly connoisseurs who preferred the clearest glass they could get their hands on,” explains Gry Hoffmann Barfod of Aarhus University’s Department of Geoscience. She continues:
“For a geochemist, it has been a privilege to work with the fantastic material, and to discover how relevant the knowledge stored here is for our society today.”
Interdisciplinary research
Gry Barfod, Sren Sindbaek, professor of archeology at the Danish National Research Foundation’s Center for Urban Network Development (UrbNet) at Aarhus University, and Claus Feveile, museum curator at the Museum of Southwest Jutland specializing in the Viking Age and Ribe’s earliest history, collaborated on the interdisciplinary study.
“The most outstanding achievements at the Ribe trading site were not just the products, but also the circular economy and their awareness to preserve limited resources” states professor Søren Sindbæk.
And museum curator Claus Feveile comments:
“These exciting results clearly show the potential of elucidating new facts about the vikings. By combining our high-resolution excavations with such chemical analyses I predict many more revelations in the near future.”
Søren Sindbaek and Claus Feveile headed the archaeological excavations of the Northern Emporium Project from 2016-2018, where new high-definition approaches for the first time allowed for a resolution down to a few decades within the extremely well-preserved Ribe stratigraphy. The finds from the excavations are currently displayed inside reconstructed replicas of the beadmakers’ workshops in the new special exhibition at the Ribe viking museum.
