Oslo Opera: The Yellow Marble

OSLO, Norway – The new National Opera House here hasn’t hosted a production yet, but its marble façade is becoming a sour note.
It’s not a case of substandard stone or improper installation. It’s that the white marble from Carrarra, Italy, is turning yellow.
Oslo’s Aftenposten reported in late November that yellow streaks are appearing on interior and exterior installations of La Facciata at the opera house. And it involves more than just some trim – the streaking is occurring throughout the 269,000 ft² of marble used to clad the building’s roof, forecourt and foyer floor.
The culprit, it turns out, is moisture. How to fix the problem, however, is up for debate.
Dealing with wet conditions is an everyday job at the fjordside location on Oslo’s harbor. The best guesses so far involving the marble discoloration include dealing with damp ground; a possibility of building on concrete that didn’t cure properly; and covering the entire structure, including the installed marble, with plastic sheeting for months.
In mid-December, Aftenposten noted that SINTEF, a research foundation based in Trondheim, Norway, studied the yellowing and offered two options to fix the problem: Dry the stone, or treat it with hydrogen peroxide.
SINTEF advocated taking the former route by uncovering all the marble and, in the case of interior installations, turning on the floor-heating system. Giving the stone the bottle-blond treatment with peroxide would be a last resort.
University of Oslo professor Tom Andersen told Aftenposten reporters that SINTEF’s report may be superficial, since the research foundation couldn’t give the exact cause of the yellowing. He believes the discoloration is pyrite that’s oxidizing in the marble, permanently staining the marble.