A north Brisbane college wants to sell two "iconic" signs painted for World Expo '88 by Ken Done to someone willing to store them ahead of the event's 30th anniversary.

The faded steel signs which spell out "Australia" have been advertised for $5,000 on social media by students on behalf of Arethusa College.

Arethusa College student Kurt Jones lists the Expo '88 signs for sale on social media. ( Facebook: Kurt Jones )

People who visited the Australia pavilion at South Bank 30 years ago have fond memories of the bold, bright sculptures that now languish unmaintained in a cow paddock just off the highway.

Fourth-generation sign-writer Rodney Smith, who crafted the letters for the Expo, told ABC Radio Brisbane they should be bought by a museum and stored indoors to prevent more damage.

He also cast doubt on whether it was possible to restore the original lettering.

"You may as well start again, it'd be cheaper.

"I think it's done well to survive as long as it has actually."

Ken Done's sculpture of the word Australia was bold and bright. ( Supplied: State Library of Queensland )

Never built to last

Original plans for the signs intended them to be crafted out of aluminium which was less likely to corrode over time.

"It was built in steel because it was only going to be a short-term product just for the Expo," Mr Smith said.

The letters were painted with rust protector before being covered with bright shades of house paint carefully selected by renowned artist Done.

One set of letters stood at the entrance of the Australia pavilion and the other formed a sculpture at the exit.

Mr Smith said it took his team six weeks to construct the letters.

The sign is rusting away in a north Brisbane cow paddock. ( Facebook: Kurt Jones )

Moving the completed signs to the pavilion site was such a big job that he initially considered airlifting them in.

"At one stage we were going to fly it in by helicopter but we couldn't get a permit to do that.

"We made it all in smaller pieces we could get on a truck ... took it down in the middle of the night and then put it together on site.

"It was quite an undertaking at the time because it was all hand-built."

When Mr Smith inspected the signs a few years ago he said they were in a pretty sad state.

"I didn't consider it was viable to [restore]."

Past attempts to save signs failed

Peter Rasey, people's committee chair for Expo '88's 30th anniversary, said there was an attempt to relocate the signs to Brisbane Airport ahead of the 25th anniversary but the deal fell through.

Ken Done's Expo '88 sculptures were sold to a local college. ( Facebook: Kurt Jones )

"They were just salvageable at that point in time," he said.

"When I finally convinced the college that they should donate them to the project, the manager out at the airport changed directions so the opportunity was lost."

Mr Rasey said the letters were purchased by the college for $10 from the "visionary" Done after the Expo.

He said the ungalvanised sheet metal letters suffered in the elements.

"Cows are indiscriminate, they don't look at the word Australia and say, 'I shouldn't deface this'," he said.

"It's the urine and the faeces that have done the damage."

South Bank boss considers saving sign

South Bank Corporation chief executive Bill Delves said the discovery of the old Expo signs languishing in a paddock was a revelation to him and flagged their potential to be included in next month's celebrations.

"How could we not consider something so iconic in such an iconic location," he said.

Mr Delves said all sorts of trinkets had come out of the woodwork during the callout for Expo memorabilia ahead of the anniversary.

"We haven't seen anything as big as the sign yet," he said.

"I don't think this is going to be a simple project by any means."