What is corten steel?

In 1930’s America, coal wagon manufacturers noticed certain steel alloys developed a layer of rust that instead of corroding the steel when exposed to the elements, protected it. Under the brand name Cor-Ten – an abbreviation of ‘corrosion resistance, tensile strength’ – the lasting, earthy, orange-brown patina of these alloys soon gained popularity among architects (possibly the most famous example being the John Deere World Headquarters in Illinois, designed by Eero Saarinen) that continues to this day. The alloys continued to undergo development to improve their strength and durability. In time, the name lost its hyphen and become a generic term. Corten steel is also known as weathering steel or weathered steel.

How does corten steel gain its patina?

Corten steel is a mixture of steel and alloys that varies according to the grade of corten steel. Before exposure to the elements its dull, dark grey surface might suggest the wrong product has been supplied, but over time it will develop a patina that is unique to each piece. Humidity, warmth, and airborne pollutants all contribute to this natural palette, while oxidation will be faster in more exposed locations and if water remains on the surface rather than draining away.

corten steel

Why is corten steel so popular?

Corten’s popularity can be attributed to its strength, durability, practicality, and aesthetic appeal. With a tensile strength of 68-78 KSI compared to 45-64 KSI for galvanised steel sheet, corten is capable of withstanding greater forces before buckling or breaking.

The naturally-occurring protective oxidised layer protects corten against corrosion in most environments. Corten requires no painting or ongoing surface treatment. If the oxidised layer is scratched and exposes new steel, this will rapidly oxidise and blend in with the rest of the surface. The chief reason for its popularity in landscape architecture must surely be the raw, natural beauty of its patina that blends effortlessly with other natural materials such as wood and stone and provides a striking contrast to the lush greenness of foliage.

What do corten steel planters look like?

Corten steel planters bring structure to private, commercial, and public landscaping projects. Available in a range of standard designs or bespoke creations, they can incorporate features such as benches, lighting, and tension cable systems or combine with coordinating screens that add drama and seclusion.

Corten steel planter at 245 Hammersmith

Can I see examples of corten steel planter projects?

Of course. We have an extensive portfolio of impressive projects we have worked on and can be browsed on our projects page but two projects with extensive corten steel planters are 245 Hammersmith and Royal Mint Gardens.

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corten steel planters at Royal Mint Gardens