Conservation and care of Batavia

Following their recovery, the timbers were kept wet with seawater and stored in plastic-lined holes on Beacon Island. To keep them wet during transport to the Museum’s Materials Conservation laboratory in Fremantle, they were wrapped in seawater and fungicide-soaked hessian and sealed in large plastic bags. In Fremantle, the timbers were transferred to large tanks and allowed to desalinate (remove salts) in fresh water for about two years. During this time, the Materials Conservation team researched the best option for treating the waterlogged timbers. 

They determined that impregnation with polyethylene glycol (PEG), a water-soluble wax, was the most appropriate treatment. In this treatment, the wax lines and reinforces the cell structure of the wood to impart strength and reduce further degradation. It was achieved by immersing the timbers in heated baths of increasingly concentrated PEG over a period of two to three years. After the PEG impregnation, the timbers were air dried using a slow dehumidification process. The temperature and relative humidity in the dehumidification chamber were gradually altered over six to twelve months to match the conditions in the new display gallery in Fremantle. 

Between 1981 and 1987, the conserved hull timbers were reconstructed on a purpose-built frame utilising the original bolt holes where possible, which allowed for individual timbers to be removed for follow-up treatment. This design has been very important for the ongoing conservation of the timbers. 

The hull section being reconstructed on the custom-built frame, 1988. 

Credit: WA Museum, BT/T/403  

By the mid-1980s, the timbers were starting to show signs of acid formation following occasional periods of high relative humidity. The Materials Conservation team investigated methods for timber deacidification and opted for treatment using gaseous ammonia. After their successful treatment, the timbers continued to be monitored. While the acidity levels had been stabilised, some timbers remained very fragile. New work began to find a suitable agent that would impart the timber with strength, flexibility and hardness, and be compatible with the earlier PEG treatment.  

Following this, in the early 2000s, the Materials Conservation team continued to work on the hull, finding suitable treatments to improve the look and strength of the timbers, particularly where they had been cut with pneumatic chainsaws during the excavation. Around this time, the Museum updated its processes around monitoring relative humidity, and the environmental systems in the gallery were replaced to maintain a stable temperature and relative humidity levels. These changes have ensured the long-term stability of the timbers. 

Today, the preference is to preserve archaeological timbers where they are found, rather than removing them. In cases when this not possible, the PEG treatment—used on the Batavia timbers in the 1970s—is still the most common treatment for the preservation of waterlogged, archaeological timbers. 

The hull section on display in the Batavia Gallery at the Shipwrecks Museum, Fremantle. 

Credit: WA Museum