How Corten Patina is Formed

How Corten Patina is Formed

Corten steel has a specific composition that enables it to develop a characteristic rusty surface layer, known as a patina.

The corten patina offers several advantages and uses. Firstly, it forms a protective layer on the steel surface, preventing further rust penetration into the material's depth. This prevents corrosion and extends the steel's lifespan. Secondly, the corten patina has aesthetic value. Its rusty color creates a natural and rustic appearance, making corten products stand out in both modern and traditional gardens.

Another advantage of corten products is their low maintenance requirements. Once the patina has formed, there's no need to paint or further treat the steel material. Corten steel is often used in outdoor environments because it's resistant to weather conditions and doesn't require regular maintenance.


Products from our portfolio are usually delivered in a raw state, making them virtually indistinguishable from traditional steel products. Simply place the corten product outdoors and expose it to natural weathering. The color and surface structure of the patina will change over time. The rusting process is completed after approximately 1.5 to 3.5 years. During this time, a barrier layer resistant to weather conditions is formed, protecting the product from further corrosion. To create this barrier, it's important for the product to be exposed to changes between wet and dry weather. If this occurs, the appearance of your corten items will interestingly change and darken into a noble deep purple tone. If changes between wet and dry weather are prevented, the patina cannot develop, and weather resistance cannot be guaranteed.

If you want to stop the patina formation process and maintain the appearance after several months, you can treat the product with lacquer or oil. The rusty material is preserved as the oil penetrates deep into the pores and retains air and moisture. Repeat the treatment as needed. However, the natural rusting process and thus the formation of a weather-resistant barrier layer is irreversibly interrupted.

If the product is not treated in any way, it will acquire a very dark shade over the years. Without treatment with paints, oils, etc., the copper, chrome, nickel, and phosphorus contained in this steel contribute to the formation of a natural protective layer, firmly adhering to the surface, called a patina, which, in addition to weather resistance, also exhibits highly attractive and aesthetic properties.

When developing the patina, special attention must be paid to ensuring that the products are not exposed to permanent moisture. Changes between wet and dry conditions must be guaranteed. Rainwater should not accumulate anywhere; it should have the opportunity to drain evenly. Corten steel should also not be exposed to aggressive weather, such as excessively salty air near the coast or direct exposure to industrial vapors.

Depending on the weather and environmental influences, different rust colors appear on the surface. It may even happen that objects from the same production batches have different colors, but products become more and more similar as weathering progresses.

Rusting is a natural process. The patina typically develops from light brown to brown to dark brown-purple, with a grainy surface. The color effect varies depending on the light and weather conditions. The surface grain may differ for individual products. Each object should be considered unique, and its development cannot be fully predicted. In general, it can be assumed that the warmer and lighter the environment, the lighter the surface remains; at low temperatures and high humidity, the color darkens.


Corten steel is a natural material. Different colors or graininess of the material, as well as scratches and black discoloration, are normal and define this material. They are not a defect or reason for complaint.

If airflow is prevented, for example, if the protective film is in direct contact with the surface of the product during transport, the patina may darken. Similarly, when fallen leaves accumulate on the surface.

Over time, under appropriate weather conditions, most irregularities will be leveled out. However, we would like to point out that the surface of corten will never look uniform. Corten can be humorously referred to as "shabby chic," meaning that traces of imperfections are part of the concept.


You can adjust the surface of corten steel with simple means and remove irregularities, such as black spots, scratches, etc., and even out and thus accelerate the formation of the desired patina. For this purpose, a standard kitchen sponge with one rough and one soft side is suitable.

Use the rough side of the sponge to roughen the surface, always work in the direction in which rainwater drains (always from top to bottom). You can also use coarse sandpaper and lightly sand the surface (always in the direction of flowing water).

Then wipe the surface with the moist soft side of the kitchen sponge, again from top to bottom. Repeat the process as needed.


Direct contact of rusty components with other materials - such as concrete, natural stone, wood, etc. - can result in rust contamination. Rust stains are difficult or impossible to remove. Therefore, if direct contact with other materials cannot be avoided, use a pad, such as felt, if necessary.

Clothing soiled with rust can be washed in the washing machine at approximately 30 degrees.


As a home remedy to accelerate patina formation, you can use a diluted vinegar solution (approximately 1 part vinegar to 3 parts water). Spray the diluted vinegar essence evenly on the patina surface. After a few hours, the rust surface usually changes. When treating with a heavily diluted vinegar solution, ensure that the material is only slightly moistened with a sprayer and that excess liquid can drain, otherwise unsightly spots may form, and the material may be attacked in such a way that it can no longer rust evenly.

You can also find professional products on our website to accelerate patina formation.

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