Maritime Archaeological Conservation at the Department of Materials Conservation
The special micro-environments created by the interaction of corroding iron artefacts and the marine organisms that colonise the objects has provided special protection of delicate materials from the ravages of the sea. Without this form of encapsulation material such as lace from the Batavia would never have survived. Organic materials such as timber will continue to degrade under the covering layers of sand and coral as bacteria eat the cellulose polymers in the structure of the wood. The lost material is replaced by water and the waterlogged wood can contain up to 850% water, based on the oven-dried weight of the wood. Impregnation of the timbers with solutions of polyethylene glycol, a water soluble wax, helps to stabilise the timbers and to prevent collapse when they are carefully dried out. Treatment of each batch of the Batavia timbers took up to four years desalination and impregnation before they were dried and put on display. Metals such as iron will continue to corrode at a very rapid rate after they have been excavated and require immediate on-site conservation treatments to retain all the original details on the surface layers. Treatment of a cannon that has corroded for 350 years is completed in seven years of electrolysis. The corrosion studies of metals on the sea bed have led to the development of new site management methods such as in-situ conservation treatment of iron cannon and anchors by using sacrificial anodes. Maritime artefact conservation, preservation and research established the international reputation of the department. Apart from the conservation of shipwreck materials the department treats the artefacts in the collections of the History and Anthropology departments of the museum as well as material from the collections in the branch and regional museums. Another important part of their work involves collaborative research with the Department of Aboriginal Sites on the conservation of rock art. |

The Conservation Department of the Western Australian Museum is based at the Maritime Museum in Fremantle where twelve staff care for the collections. Because of the close collaboration between maritime archaeologists and conservators it has been possible to develop many new methods of stabilising shipwreck materials. By diving on the wrecks and taking their laboratory instruments with them, the conservators are able to study the end results of long-term corrosion and degradation processes before the sites are disturbed. Without the team work that is involved in these joint projects valuable data would have been lost and the understanding of the corrosion mechanisms and the processes controlling the degradation of shipwrecks would never have been elucidated.