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  • Indaten®

Indaten® ... a magical steel, in harmonious dialogue with nature

Like a fine wine, Indaten® weathering steel is enriched by air and enhanced with age. When exposed to the natural environment, this magical steel develops a beautiful patina that serves as protective armour and makes way for the steel’s trademark purplish brown colouring.

As a maintenance-free material that can last for 80 years, Indaten® weathering steel has been the product of choice for buildings, bridges and sculptures since 1930.

Weathering steel, in brief 

Indaten® develops its patina following exposure to the atmosphere. The first oxide layer appears within a few weeks, with the final colour being achieved within one to two years. The finish can last, without maintenance, for at least 80 years. The steel can also be pre-oxidised.

The primary alloying material in weathering steel is copper, at concentrations up to 0.55%. The copper produces a homogeneous and regenerating protective layer over the surface, which slows corrosion and ensures the integrity of the underlying steel.

The Indaten® advantage

Combining durability and natural beauty – that’s the Indaten® advantage. Unlike other building materials, Indaten® weathering steel does not need the extra expense of corrosion protection. That’s because it protects itself, naturally!

When exposed to the natural environment, this fine-grain, high-strength structural steel develops its unique, purplish brown oxide layer – known as the patina – that serves as a suit-of-armour, protecting the steel from the corrosion that other materials succumb to.

  • No painting or chemicals necessary
  • Aesthetically pleasing
  • Natural protection against corrosion
  • Reduced construction time
  • Less maintenance costs
  • Eco-friendly and 100% recyclable
  • Longevity


Indaten® is the material of choice for many architectural, decorative and green building projects. Its durability, low-maintenance and unique aesthetical appeal make it ideal for cladding, bridges, chimneys, pylons, doors, decorative screens, floors, sculptures… and so much more! In fact, Pablo Picasso didn’t hesitate in choosing the natural and long-wearing finish of weathering steel when building his famous sculpture that still stands today in Chicago’s Daley Plaza.


The protective layer is built when the steel surface is exposed to an alternatively wet/dry environment. Building an optimal protective layer greatly limits corrosion rates and prevents a reduction of the steel’s overall thickness (see graph below).

All about the aspect

The patina’s aspect depends on time, the average temperature of exposure and wetness. The aspect is also influenced by such things as the concentration of SO2 or chloride content in the air. For example, when used in an industrial environment, the patina tends to develop a darker colour than when used in rural areas.

Over time the patina will transform from its red-orange colour to a dark, purplish brown coloration. Although the process can take up to two years, it can be accelerated with sandblasting. In fact, to ensure a homogeneous colouring of the patina, sandblasting is encouraged.

Welding and joining

Indaten® 355 enjoys excellent performance with all common welding processes. However, when using weathering steel, specific fasteners are required. It is highly recommended that you avoid having your weathering steel come into contact with aluminium, copper, zinc or stainless steel.
Always use an elastomer to prevent contact between the bolt and the panel.
The best solution is to use fasteners made of weathering steel.

Brand correspondence

Indaten® satisfies the requirements for EN 10025-5:2005 standard.