Corten, or weathered steel cladding, is corrosion resistant while maintaining tensile strength. By adding alloying elements (copper, chromium and nickel), the rust film congeals on the surface and virtually stops all further rusting.
While other metals used in construction are designed to resist corrosion, Corten invites rust to form on its surface. The rust itself forms a film which covers the surface and forms a protective layer. You don’t need to treat it and you certainly do not paint it: it’s all about making rusty steel look attractive.
When it’s supplied to site, it looks just like you’d expect sheet steel to look, all black and shiny. Put it up against the elements and the rust gradually takes hold. It first turns a streaky yellow, which tones down to orange and after a decade or two this all goes a gorgeous dark-brown purple colour.
Rusting Corten should in theory last a couple of centuries, provided the climate is not too hostile — it doesn’t like sea salt, as this tends to eat through the congealed rust layer.
While it is largely rust-proof, there are inevitably small amounts of rust which tend to pool underneath the installation. It is worth therefore paying attention to locating it above surfaces that don’t stain or will be disfigured in any way.
Yes – it’s no longer the preserve of the cutting edge and it is beginning to move mainstream. In fact, it can be fixed in a number of ways, depending on its use.