296 Chapter 11
4 Conservation of Archaeological Wood
The appearance of waterlogged archaeological wood can be highly deceptive,
often disguising the fact that part or the entire artefact may now be a highly-
deteriorated matrix of lignin, carbohydrate debris and minerals, which is sup-
ported by water. The chemical changes that occurred during exposure to the
underwater marine environment will have invariably weakened the wooden
object, making it extremely susceptible to ambient conditions. Without active
conservation, irreversible shrinkage will take place and destroy the object.
There are two chemical problems that need to be addressed during the
treatment of waterlogged archaeological wood. First, the degradation of
chemical components of a wooden object is the direct result of long exposure
in both seawater and anoxic marine sediments. Second, the object will have
become contaminated by minerals (mainly iron and sulfur compounds). The
first problem is considered irreversible, involving the structural breakdown
of hemicelluloses and cellulose (Figure 16) by chemical and biological
processes. Conservation treatments of ancient waterlogged wood, therefore
aims to control these processes as the object is transferred from the water-
logged state to a dry and stable condition.
Conservation in the context of waterlogged archaeological wood must
remove mineral inclusions and stabilise the size and shape of the object. In
addition, the conservation treatment should be reversible, and give long-term
stability. All treatments of waterlogged archaeological wood should adhere
Figure 15Covering of exposed archaeological timbers with Terram 4000 (geotextile). Note
the growth of marine plants on Terram surface
(After Pournou, 1999)