The Guggenheim Museum in Bilbao is to be covered in foam in an attempt to restore the shine of its titanium cladding.
A specially developed chemical solution, which the museum says is similar to shaving foam, will be tested on patches of the building in the next few months.

If successful, abseilers will apply the foam to the entire building.

"It's like shaving foam," said museum spokesperson Maria Bidaurreta. The solution has been developed by Basque chemical company Inasmet.

A row broke out earlier this year over the cause of the mysterious staining that has affected about 10% of Frank Gehry's design.

Titanium is not supposed to tarnish; instead, the architect claimed that the dull brown streaks were caused by the oxidisation of chemicals used to fireproof the steel structure beneath the titanium shingles, which leaked onto the cladding during construction.

Gehry claimed that the building should have been cleaned immediately after completion, and now fears that cleaning work will leave the building's surface looking patchy.

The museum vigorously denied claims that sections of the cladding will have to be replaced. "There's nothing to repair. It's just dirty," said Bidaurreta.