Shipshape: conserving a model of the Princess of Tasmania
Learn how our conservators addressed metal corrosion on a striking 1950s ship model in the State Archives Collection.
The State Archives Collection holds several models of ships and an engine constructed at the State Dockyard, Newcastle, during the dockyard’s operation in the 20th century. These were created by model maker Phil Andreas and all but two of the models are now stored at the Western Sydney Records Centre, where they always catch the eye of visitors.
When the models came into our care, conservators noted that at least two displayed corrosion of the ship model fittings. One of these is the model (RNCG-4344-16-[A3580 8]) of the Princess of Tasmania, a vehicle and passenger ferry built to modernise the Bass Strait crossing between mainland Australia and Tasmania. When the ship was launched in 1958 it was the largest vessel ever built in Australia.
Lead and lead alloys were popular components in ship models, as they were readily available, soft and easy to melt. The models were frequently mounted in wooden boxes with glass lids for display. However, this housing creates a micro-environment for chemical reactions between the lead and other metals, wood and adhesives to form a corrosion product, sometimes mistaken for mould, that we often see on old ship models. This deterioration is visible on the deck of the Princess of Tasmania model as a fluffy white powder.
This deterioration is difficult to prevent and treat, but we can slow it down by improving ventilation to reduce the build-up of harmful gases that are created over time as the model components age.
Supervising Conservator Tristan Congreve devised a treatment plan to remove visible corrosion from the Princess of Tasmania model and improve its storage to prevent future degradation. The plan involved:
- Taking the glass lid off the model base
- Removing the white flakes, powder and other deposits from the model and base
- Replacing the top pane of the glass lid with a breathable board and fabric panel to improve ventilation and reduce the build-up of harmful gases
The treatment required careful planning and collaboration with many colleagues. First, Tristan undertook a risk assessment of the process, as there were physical risks involved with moving the model, as well as health concerns around working with a substance that we suspected was lead, which can be harmful if ingested. To counter these risks, we borrowed a specialised heavy-metals vacuum cleaner from our colleagues in Collections Care at Rouse Hill Estate and co-opted some colleagues at the Western Sydney Records Centre to help move the model and lift the lid.
On treatment day the model was manoeuvred out from its storage space and placed onto pallets.
The glass lid was then unscrewed and carefully lifted off its base.
Tristan collected samples of the white corrosion and other deposits for later testing with the help of conservators from the State Library of New South Wales and their portable X-ray fluorescence analyser. The testing will confirm what the corrosion product is and if it contains lead. Tristan then brush-vacuumed the model and its base to remove dirt, and all deposits.
Before
After
When the cleaning was completed, Tristan began working on the glass lid in order to improve ventilation. First, he removed the top pane of glass.
The top pane was then replaced with a panel of board and Reemay (a breathable non-woven fabric), which allows air to circulate to reduce the build-up of harmful gases inside the lid.
The model was then carefully manoeuvred back into its storage location. After a final clean of the exterior glass, the Princess of Tasmania model is now in ‘shipshape’ condition, ready to fascinate visitors once more.
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Lang Ngo
Senior Advisor, Conservation
Lang Ngo is the Senior Advisor, Conservation, at the Western Sydney Records Centre, Museums of History NSW. Lang is a paper and photographic conservator with over 25 years’ experience working with library and archive collections, most recently at the State Library of New South Wales where she led the preventive conservation and conservation for digitisation teams. Lang has a Bachelor of Applied Science in Cultural Materials Conservation (specialising in paper conservation).
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