Gallery in a pickle as Hirst's cow and calf spring a leak

Buying a work by Damien Hirst is always going to be a costly exercise. He is, after all, the highest-selling living artist on the planet whose pieces command unprecedented prices. So spare a thought for Oslo's Museum of Modern Art, which was forced to return the artist's installation of a bisected cow and calf for repairs after the tank of formaldehyde they were in sprang a leak.

Just over a year after Hirst's famous shark was found to be suffering from rot, a second pickled piece, the 1995 Turner Prize-winning Mother and Child Divided, had to be sent back to the artist's studio for emergency repairs, The Art Newspaper will report in its October edition. The tank was on display at the Astrup Fearnley Museum of Modern Art in Oslo when the leak was spotted. The work was immediately sent to the artist's studio in London for emergency repairs. It brings into question the longevity of contemporary works of art that are made with unconventional materials. Gunnar Kvaran, the museum's director, said the damage was caused by a flaw in the glass, and some formaldehyde was lost. "Our insurance will probably have to cover the costs of conservation," he added.

Although only one case in the work was found to be damaged in June, all four parts of the installation were sent back to Hirst. The work was the gallery's most popular and will not be returned until next year.

Grete Arbu, head of collections at the museum, said it had been discussing conservation of the work with the artist before the leak was discovered.

"It had been installed permanently in 1997 and it was just getting tired," she said. "The pressure inside the container is enormous. We just noticed a small leak on the floor beneath the glass, and we sent it back within the week.

"Formaldehyde is very dangerous material. The same container will be kept but the layers of glass will be replaced. We could see it needed to be conserved.