Australians have the chance for a relatively rare glimpse of some of the most important documents in the country's history, with the nation's "birth certificates" on show at the National Archives.
Three of the seven precious documents that changed Australia's relationship with Britain are so fragile that their dark covers are taken off only for occasional viewing by the public, including the Easter and Anzac Day long weekends.
"To put it in context, if you think of the constitution and the Bill of Rights in America, it's that. But Australians being Australians it's in our nature to downplay these things," senior conservator Cheryl Jackson said.
Of the three documents on parchment, two - including the Commission of Assent which enacts the Australian constitution and the founding of the Commonwealth - bear the signature of Queen Victoria, which make them irreplaceable.
"About 18 months ago we did some analysis on Queen Victoria's signature on two of the documents. It's written in iron gall ink which is normally fairly dark, but her signature is fading quite dramatically," Ms Jackson said.
The revelation led the National Archives to restrict viewing of the documents, as the ink is chemically fragile and sensitive to light.
"We keep a tally of all the amounts of exposure in 15-minute lots and I think it's given us 500 years."
Exhibition manager Caroline Webber said the decision to restrict viewing was to help as many people as possible see the documents in future years.
"Although access is limited to special peaks or if there's a school group or tours, it means that we can have them on display for longer," she said.
While the text on the documents is reasonably dark and readable, the Queen's signature is much lighter.
"The text in the past has been retouched in spots, but the signature has not because it would have been forgery and probably treason to retouch Queen Victoria's signature," Ms Jackson said.
"So there's nothing we can do to re-establish that signature; once it's gone, it's gone."
The Federation gallery displaying the documents has a permanent illumination of just 20 lux, and there is no UV content in the lighting to protect the documents, which are encased in reinforced glass to protect them from atmospheric pollutants and curious people.
"When you get this under the microscope, you can see there is even parts where the iron gall ink is lifting off the parchment, so they're physically fragile as well as chemically fragile," Ms Jackson said.
The story National Archives battle to preserve nation's 'birth certificates' first appeared on The Sydney Morning Herald.