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Opening a new window onto medieval glass trade and technology

Periodic Reporting for period 1 - WINDOWGLASSMED (Opening a new window onto medieval glass trade and technology)

Reporting period: 2020-09-01 to 2022-08-31

This project will open a new window onto trade and contact in Early Medieval western Europe, applying multidisciplinary research methods to well-dated samples of glass to investigate its production, trade, and recycling from the 7th to the 10th centuries AD. While the chemical and isotopic analysis of glass is already used as a proxy for questions of trade and contact, the data currently available for this period are sporadic, with many samples coming from poorly-dated archaeological contexts. The Early Medieval period witnesses a major compositional transition from the use of natron to plant ashes in its manufacture, but the timing of this technological change – and its relationship with Early Medieval recycling practice – needs a better temporal resolution than is currently available.
Historical research at one of the leading centres for the study of the Early Medieval period will be paired with cutting-edge scientific analysis, allowing the first detailed mapping of the changing production technologies of glass in this period, the trade routes followed by different glass ‘recipes’, and the social and economic factors influencing practices such as recycling.
This project will be the first detailed multidisciplinary study focused on well-dated 7th–10th century to create a detailed, chronologically-resolved map of Early Medieval glass in western Europe, reflecting both trade patterns and practices such as recycling. It has four major objectives:
1. Scientific analyses – trace element analysis (with LA-ICP-MS at the Field Museum, Chicago) and isotopic analysis (BGS – Keyworth) of well-dated vessel fragments from Western Europe.
2. Creation of a database of scientific results plotted against archaeological data and geographical coordinates for the samples and assemblages in question.
3. Research into and mapping of major Early Medieval trading sites, glass imports, trade routes, and exchange networks in the selected Western European areas, at DARMC (Harvard).
4. Creation of GIS distribution maps based on Objective 2, combined with Objective 3, and inclusion of the results in the DARMC online dataset (

The work performed so far focused on:
• Organising sample collection/fieldwork
• Sampling glass from Italy, Spain, and Denmark
• Performing scientific analysis of the glass (LA-ICP-MS)– Fields Museum (Chicago, USA).
• Data collection and evaluation - Western European glass published so far.
• Creation of a database for EM Western glass and available comparison data.
• Data evaluation - LA-ICP-MS analysis
• Training - R-language
• Creating R environment suitable for glass data analysis
• Training in how to create a GIS map with R
• Presenting the project at conferences (AIHV 2022) and invited workshops and seminars (Harvard University, Oxford University).
• Grant writing for isotopic analysis (NERC grant, UK).
• Training – (ILTHE - The Introduction to Learning and Teaching in Higher Education)
By the end of this project, the trace elements and isotopic data available for Early Medieval Western glass production will increase substantially. The creation of multi-layered distribution maps focused entirely on vessel glass will allow us to finally trace not only the diffusion of specific chemical compositions but also the impact of glass production trends such as recycling and mixing.
The database created will be published online on the Archaeology Data Service in order to make the results available to the public and to other researchers.
In addition, the acquisition of Sr and Nd data on Spanish, Scandinavian and Italian glass will allow making some concrete hypotheses about where the glass was produced in the first place. The data acquired will also be tied in with the existing knowledge on trade routes in order to trace back the potential exchange routes and network where raw glass and cullet were traded along to Western Europe.
Finally, a new guideline on how to treat and analyse glass data in R will also be published.