Differences in birch tar composition are explained by adhesive function in the central European Iron Age

Area of Science:

• Archaeological Science
• Materials Science
• Organic Chemistry

Background:

• Birch bark tar was a key adhesive in prehistoric Europe.
• Adhesive use diversified with conifer resins and beeswax in later periods.
• Limited large-scale studies exist on Iron Age adhesive technologies.

Purpose of the Study:

• To investigate adhesive substances used during the Iron Age in north-eastern France.
• To provide a broader perspective on Iron Age adhesive technologies.
• To analyze the composition and function of identified adhesives.

Main Methods:

• Organic residue analysis of 65 samples from 16 archaeological sites.
• Analysis of residues from ceramics, vessel coatings, repaired items, contents, and lumps.
• Statistical analysis of molecular composition to correlate with adhesive function.

Main Results:

• Birch bark tar was identified as a well-preserved adhesive used for at least 400 years.
• Pinaceae resin and beeswax were also identified, though less frequently.
• Molecular composition differences were observed, correlating with adhesive function.

Conclusions:

• Birch bark tar remained a significant adhesive throughout the Iron Age in north-eastern France.
• The study provides insights into the production, processing, and use of birch bark tar.
• Findings contribute to understanding Iron Age material culture and technology in the region and beyond.