How the Sydney Opera House tiles stay white
The self-cleaning tiles never get a scrub down by anything but the elements. Danish architect Jorn Utzon planned it that way, the spherical shape of the shells allowing for good drainage so that cleaning would not be necessary. He worked on the tiles, made from clay with a small percentage of crushed stone, for three years with Swedish company Höganäs.
In the early 1960s, more than 1 million “Sydney Tiles” were shipped from Höganäs in Sweden. Some 940,840 cover the building now and the remainder are in an off-site storage facility.