GUEST POST: Preservation of Leather Artifacts in Archaeology

That's right...a rare guest post on Matsukaze workshops; my Apprentice's partner wrote out this gem, and I offered to host it until (and if) he creates his own webpage, as it's useful and well written information--plus it's far easier to share a webpage than a document.  Factors for preservation for organic materials is something which I have regularly needed to reference when recreating or discussing archaeological finds.
        Maistre Bran

Preservation of Leather Artifacts in Archaeology

Leather artifacts bear crucial information on past civilizations, craftsmanship, the norms of society, and daily life. However, organic materials, mainly leather, are prone to several problems that hinder their preservation at archaeological sites due to their sensitivity to environmental conditions. The scarcity of preserved leather at archaeological sites poses enormous challenges to historians and conservators. This scarcity is not by chance, but by a combination of environmental conditions, including the composition of the soils, moisture levels, and the practices of burying artifacts. This study will explore some of the factors controlling leather preservation at different archaeological sites. It will give insight as to why leather items survive across the timeline versus other perishable materials. This study reinforces these factors as the best-understood contribution of environmental and human influences to archaeological survival by comparing extant examples from the Birka, York, and Vindolanda archaeological sites. Through this research, we aim to shed light on the complexity of ancient leather conservation, which will be the first stage in a journey to acknowledge the selective nature of leather discoveries.

Factors Influencing Leather Preservation

Preserving leather artifacts is complex and depends on many environmental and human factors that eventually influence their lives. Factors like the soil of the constitutional state, moisture in the ground, temperature, climatic conditions, and the means of burial could change the state of the leather and its appearance significantly. Every factor is critical in preserving or degrading the leather since archaeologists find preserving it with the maximum guarantee challenging.

A significant predictor of the longevity of leather artifacts relies on the form of soil they are buried in. Microbial activity in breaking down such materials fosters more acidic soils with low pH, which is typical of the decomposition process of organic materials like leather. On the other hand, more alkaline soils with a higher pH may slow this breakdown to a certain degree. However, over-alkalizations could also be equally detrimental to some extent because leather mineralizes and consequently changes its preservation status. Perhaps, in this way, soil pH balance is one of the strongest determinants of the deterioration rate of such leather goods over time.

The amount of moisture in the soil is also vital to the preservation of leather. It requires relatively limited moisture levels to keep the leather in good shape for a long time. Excessive humidity, however, results in the formation of microorganisms, which might cause leather decomposition. Waterlogged conditions, paradoxically, where there is little or no oxygen, can stop the decomposition process (Randerz et al., 2023). Therefore, preserving the leather almost in a perfect state which can be seen in some artifacts recovered from bogs and other anaerobic environments. Additionally, these paradoxes emphasize that even moisture significantly impacts the conservation of leather; as a result, archaeologists should pay more attention to these paradoxes in the relevant practices.

To a large extent, practical conservation is also heavily focused on all leather artifacts' temperature and climate conditions. The temperature often highlights a variation, typically high or low, that could ruin the leather related to artifacts. These general solutions include drying, making the leather brittle, and even cracking. Any shifts in the humidity will also substantially heighten the qualities in question. A stable and conducive temperature environment positively influences the excellent quality of the leather artifacts, making temperature an important preservation factor.

Birka, Sweden

Birka is one of the prime archaeological sites found in Sweden on the island of Björkö (The History of Birka the Viking City – Stockholm Sweden, 2016), which is indeed evident enough to bring new learning to a more general understanding of trade, society, and daily life in the Viking Age. It was established in the 8th century and inhabited until the late 10th century as one of the earliest urban centers in Scandinavia (Lund & Sindbæk, 2022). One thing that was very crucial at Birka was the acidity of the local environment and the soil. The variability in soil pH values across Birka in diverse parts of the island was critical to preserving organic materials. In places where soil conditions are more alkaline, quantities of leather objects were, to some extent, saved from quick decline. The preservation status of such leather goods depends on the prevailing micro-environmental conditions within those burial sites, such as moisture quantities and metal constituents. To shine a bright light, several sundry leather goods have been masterly excavated due to various researchers interested in the material culture and craftsmanship of Vikings.

Wallets from graves Bj 543. Taken from Arbman 1940: Taf. 130, 132-133.

Bj 750

Bj 904

The York Archaeological Site, England

The York Archaeological Site, specifically the site at Coppergate, has produced a wide variety of Viking Age findings, many of which are leather objects that have been exceptionally well preserved due to their environment. Waterlogged conditions in the soil of York presented areas where oxygen, an important indicator, was sometimes reduced to almost negligible levels for microbial activities usually responsible for the decay of organic substances. The unparalleled preservation armature at Coppergate has made the recovery of a relatively wide range of leather goods possible, from shoes to bags and belts (Psarros et al., 2022). The preserved ancient leather materials hold valuable information for archaeologists and historians to get insights into the design, functional aspects, and prevalent construction techniques. The high level of preservation of leather from the site at York reinforces the critical role of environmental conditions in which archaeological conservation work takes place and emphasizes the importance of specialized conservation techniques needed to stabilize and conserve this delicate organic material.

One of 42 pairs of well-preserved leather skates found. (JORVIK Artefact Gallery, n.d.)

Vindolanda, Roman Britain

Vindolanda, an extended auxiliary fort of the Roman military base in what is today northern England, may have extended the best-looking cohort of fashions from the period (Schávelzon, 2020). It is undoubtedly a vibrant site. Flourishing with plant biomatter due to the richness of its soil, makes it a damp environment. Absolutely no climate-controlled storage meant that a tremendous archaeological resource was produced. It means that at the site, Roman builders created a charging anaerobic positive environment by distributing turf and clay over demolished buildings prior to initiating construction on previously used sites. This process efficiently sealed in the underlying layer thereby conserving everything beneath it (Why Are the Artefacts at Vindolanda Found in Such Good Condition, n.d.). This process restricted access even by bacteria and fungi, which degrade organic materials positively. This refining process can practically make it a priceless source for arguing about an otherwise practically undocumented period of the Roman Empire. 

Vindolanda Archaeological site has contributed significantly to preserving leather, wood, and other materials for over two millennia. The kind of leather found at Vindolanda is a significant and unique element in Roman military life, fashion, and culture. For example, looking at the various types of shoes, a toy mouse, and boxing gloves reveals the diversified population at the fort. Romans were steadfast in their material culture and eliminated any provincial culture's environmental issues, in the frontiers they inhabited. This gives one knowledge of Roman military logistics and personal attire, opening new insights into leatherworking techniques and styles in Roman Britain.

Various shoe types (The Vindolanda Archaeological Leather Project Update, 2021)

A Comparative Overview and Implications of Leather Preservation Conditions

The leather preservation in Birka is more relative to soil and acidity under alkaline conditions; leathers found at least some tenderness from quick decomposition. However, the conservation of the leather artifacts is not uniform across the site, and micro-environmental conditions in some specific areas are considerably relevant. In contrast, the York Archaeological Site and Vindolanda share similar preservation conditions, characterized by wet and anaerobic conditions. Waterlogged soils at York and Vindolanda are susceptible to degradation in the presence of oxygen, and active microbial life meant that decomposition was considerably slowed.

The different preservation conditions between the sites unequivocally point to the need for site-specific strategies concerned with conservation. Given the environmental considerations in this instance, adaptable plans must be worked out regarding the sites for excavation, conservation, and storage in general (Rusbridge, 2020). A good example is represented by the fact that leather prefers anaerobic, waterlogged preservation. The findings show interdisciplinary efforts in archaeological conservation through chemistry, biology, and environmental science inputs in preserving organic materials.

In conclusion, the preservation of leather artifacts, to a reasonable extent, is due to changes in environmental conditions and human practices in a given archaeological context. Birka, York, and Vindolanda archaeological sites' comparative analysis provides the aspects that contributed to the survival of leather through many centuries. In studying the methods of conserving leather, we see how leather objects are unique and precious. It equips us with practical approaches to preserving such materials to maintain traceability for future generations, aiding in our understanding of historical cultures, technological change, and its interface with the environmental ecosystem.

 

Nathan L. Meadows (Niell Mac Nyven)
Preferred “Niall De Exeter”, but Hey Nurse works too.

Society For Creative Anachronism
Laurel Apprentice to Gisla Œðikollr
Pelican Protege to Nemonna Vicana
Squire to Sir Sextus Valerius Cruscilius
Seneschal, Barony of Selviergard, Principality of Oertha, West Kingdom
03/12/2024

References

• Arbman, Holger (1940–1943). Birka I. Die Gräber. Text (1943), Tafeln (1940), Stockholm.
• JORVIK Artefact Gallery. (n.d.). JORVIK Viking Centre. https://www.jorvikvikingcentre.co.uk/about/jorvik-artefact-gallery/
• Lund, J., & Sindbæk, S. M. (2022). Crossing the maelstrom: New departures in Viking archaeology. Journal of archaeological research, 30(2), 169-229.
• Psarros, D., Stamatopoulos, M. I., & Anagnostopoulos, C. N. (2022). INFORMATION TECHNOLOGY AND ARCHAEOLOGICAL EXCAVATIONS: A BRIEF OVERVIEW. Scientific Culture, 8(2).
• Randerz, E. L. W., & Peacock, E. E. (2023). Wet archaeological leather conservation: A survey of contemporary practice in the Nordic countries. In ICOM-CC 20th Triennial Conference Preprints Valencia 18-22 September 2023 Working Towards a Sustainable Past. The International Council of Museums Valencia.
• Rusbridge, T. B. S. (2020). The culture of materials and leather objects in eighteenth-century England (Doctoral dissertation, University of Birmingham).
• Schávelzon, D. (2020). Historic Site and Historic Building Preservation: Overview. Encyclopedia of Global Archaeology, 5066-5068.
• The history of Birka, the Viking city – Stockholm, Sweden. Birka Vikingastaden. (2021, March 23). https://www.birkavikingastaden.se/en/about-birka/
• The Vindolanda Archaeological Leather Project Update. (2021, November 2). The Vindolanda Trust. https://www.vindolanda.com/blog/the-vindolanda-archaeological-leather-project-update
• Why are the artefacts at Vindolanda found in such good condition? (n.d.). The Vindolanda Trust. https://www.vindolanda.com/faqs/why-are-the-artefacts-at-vindolanda-found-in-such-good-condition
  
  
  

© Nathan L. Meadows, 2024. The Author of this work retains full copyright for this material.  Permission is granted to make and distribute verbatim copies of this document for non-commercial private research or educational purposes provided the copyright notice and this permission notice are preserved on all copies