What is Corten steel?
Corten steel (also written as Cor-Ten or corten) is an alloy steel that forms a stable, protective rust layer (patina) when exposed to the weather. This patina prevents further corrosion, eliminating the need for painting or coating. Its distinctive rust-brown colour makes Corten steel popular in architecture and art.
How does Corten steel work?
The steel contains small amounts of copper, chromium, nickel and phosphorus:
- Initial rusting — moisture and air cause a rust layer to form
- Densification — over several months the layer compacts into a tight patina
- Protection — the patina seals the underlying steel from moisture and oxygen
- Stable colour — the colour settles to a deep rust brown
Applications
- Façade cladding — panels with a warm, natural appearance
- Bridges and viaducts — low maintenance thanks to the self-protecting layer
- Garden screens — fencing, planters and edging
- Public art — sculptures and installations
- Roof edges and fascias — a durable alternative to painted steel
Points to note
In its first years, Corten steel sheds rust-coloured water that can stain concrete and natural stone below. Allow for this in the detailing.
Related terms
- Steel
- Corrosion
- Façade cladding
- Corrosion class
- Patina
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