Revolutionising the storage and display of sensitive objects
A special case developed to display the Batman land deed is a creative and scientific solution for the long-term storage and display of an important document in the National Museum's collection.
A balance must be struck between fulfilling a visitor's expectation to see key objects when they visit the Museum today – and ensuring that those same objects are available to be seen by visitors well into the future.
Museum conservators have designed and built an innovative, argon-filled case that allows precious objects to be safely displayed for 40 years and beyond.
The Batman land deed is recognised as the first acknowledgement that Aboriginal people had ownership of their land prior to the arrival of Europeans. The 1835 deed is a document drawn up between pioneer John Batman and the Aboriginal people of the Port Phillip Bay area of Victoria.
The Batman land deed was purchased in 1997 as part of the Christensen Fund and is a key object in the National Museum collection. Key objects tend to be required for display for longer periods of time so they are available to the public.
Conservators were faced with the challenge of creating a long-term storage and display solution for the deed, which was made on a sensitive parchment or vellum.
The case designed to house the Batman land deed is filled with argon gas, rather than nitrogen, which had been used to preserve the Egyptian mummies.
Argon is an inert and commonly available gas. It is heavier than oxygen, which means that any damaging oxygen floats to the top of the case, where it can be easily removed by the oxygen-scavenger blocks placed inside. Conservators are hoping for 0.01 per cent oxygen intrusion, since total exclusion is probably impossible.
Most of the technology involved is not evident to Museum visitors. A bellows at the side, which sits inside the display frame, allows the argon gas to flow between the bellows and the case, normalising the pressure to the outside. Some display cases are pressurised but the external bellows mean this case is not, which significantly reduces the chance of breaching the seals.
Conservators were initially concerned about the characteristic dryness of argon. These concerns were allayed by bubbling some of the gas through water to achieve a humidity level of 40 per cent. A hydrogrometer in the case allow conservators to see at a glance whether the correct humidity is being maintained.
The case also uses a double-sealing system to keep the gas in and to allow the use of glass in the design. Glass is a better ultraviolet light filter than other alternatives. The case also uses clever technology employed throughout the Museum, where a light is triggered by visitor footfall, so the document is only lit when someone is looking at it. This helps to reduce exposure to light.
The Batman land deed is on show in the Museum's gallery Landmarks: People and Places across Australia.
In 2008 the Museum's conservation manager, Eric Archer, said the case combined state-of-the-art technology with good mechanics.
'This is a great example of a home-grown, highly innovative work that has some real implications for the future of this Museum and others. In a way this will revolutionise the way vulnerable objects can be displayed over a long period of time,' Eric said.
The technology used in the Batman case can be applied to a variety of objects across the National Museum. The Conservation team has already collaborated other museum and gallery colleagues about applying the technology to other significant objects.