Waterlogged organic finds, such as bark, wood or fibres dating from prehistory and early history, are generally rare and, for this very reason, offer considerable potential for archaeological research. At the same time, dealing with such finds presents researchers with challenges in terms of sustainable practice, particularly with regard to conservation, documentation and storage.
Even the excavation of organic finds often requires a considerable amount of time, as great care must be taken and elaborate support structures may be necessary to prevent damage to fragile objects. From the moment they are recovered, the objects must be stored under appropriately cool and moist conditions and conserved promptly in order to prevent deterioration and their eventual loss. Depending on their condition and degree of fragmentation, conservation can require substantial amounts of time, and some materials, such as objects made from tree bark, are so rare that no optimal standard treatment has yet been established. Over the past 50 years, strong and invasive consolidation treatments have frequently been used to achieve sufficient stability. However, these can impair the legibility and identification of the bark and thus considerably hinder archaeological analysis. Today, attempts are made to intervene less extensively in the original material, but after drying the objects often remain extremely fragile, meaning that any handling may pose a risk of damage.
The issue of time and resource requirements becomes even more pronounced at sites where organic finds occur in large quantities, such as pile-dwelling sites in the Alpine foreland. In such cases, it may be necessary to select and prioritise which organic finds should be conserved permanently. Prolonged storage in an unconserved, wet and cool state consumes significant amounts of energy and merely slows further decomposition rather than preventing it. Freezing would halt biological degradation processes, but is problematic from both an energy and a conservation perspective. Even after conservation, long-term storage can be challenging because specific requirements regarding packaging materials and indoor climate must be met, which cannot be achieved without energy consumption and petroleum-based resources.
It is therefore all the more important to document all organic finds as promptly and, where necessary, as comprehensively as possible. This is particularly true of well-preserved objects on which constructional features and details such as cords or tool marks, for example from axes, are still present and can be studied. However, the necessary staff resources and specialist expertise are often lacking, partly because organic finds are still commonly regarded as less spectacular than, for example, metal objects.
The presentation discusses these challenges using bark and wooden finds as examples and drawing on the experiences of members of the Archaeobark project from conservation-restoration, dendrological and archaeological perspectives. It also advocates the development of sustainable approaches to the treatment of organic materials. Such concepts must take into account factors including the deliberate selection of finds for conservation, the relationship between effort and potential knowledge gain, available time and personnel, and different documentation methods. Ultimately, they must be both professionally and technically appropriate to the challenges involved and realistically implementable.
