About Corten (COR-TEN) - the material for trend-conscious

Glow fire bowl / bonfire / grill from Cortenfabriken. Unique fireplace in Corten steel (COR-TEN) that gilds the garden party

About Corten steel (COR-TEN), a steel with rust that is an alloy and a trendy material choice. U.S. Steel holds the registered trademark under the name COR-TEN. Corrosion resistance and tensile strength are what is meant by COR-TEN. Nowadays, it is becoming more and more common to use this durable, maintenance-free and very beautiful material for various artistic constructions such as facades, pots and sculptures.

The beauty of Corten (COR-TEN) is that it changes over time, which makes the material come alive. The steel’s earthy color is very expressive when you mix it with greenery, modern environments and other strict material choices such as glass.


Corten is a steel that achieves a beautiful deep reddish-brown color under the influence of weather and wind. Changing weather conditions transform its surface from ordinary steel paint to eventually achieve a thin protective reddish-brown rust layer.

It is an oxidation process of the steel surface that starts with the help of weather and wind. Over time, this process causes the corrosion of the Corten steel to stop. The rust layer that forms thus becomes protective of the steel and adheres to the metal surface which prevents moisture from penetrating. The insulating patina resists corrosion, requires no painting or weather insulation and does not compromise structural strength of the Corten steel.

From black metal paint to achieve an evenly rusted surface

The oxidation process of Corten steel becomes noticeable already after 6 months of outdoor use. It takes about 2 years for the steel to achieve an evenly rusty surface if you do not speed up the process by, for example, brushing on salt water. If you want to speed up the process, a good mixture consists of about 2-4 tablespoons of common table salt per liter of water. To achieve an evenly rusty surface you can use a hand spray bottle with the mixture, spray it evenly over the entire Corten surface and leave overnight. The more times you soak the steel, the faster you get a nice surface. Be sure to rinse off all salt when you have reached a surface you are happy with.

Early in the process you get a light reddish-brown color. The longer the steel is exposed to weather and wind, the darker shade of brown is achieved.

vas / rostig kruka / belysningsarmartur / Cortenkruka / exklusiv kruka  (COR-TEN / Corten / Cortenstål / rost)

Tips when using Corten outdoors

Corten is a maintenance-free and durable material. Our pots consist of 3 to 5 mm thick steel to last long term. If you want the product to withstand the outdoor environment for at least 40 years, you should use 4 mm thick steel or more.

To increase the life of the Corten steel, one should avoid water constantly resting against the Corten steel as this means that the corrosion process continues with undiminished strength. If you buy a Corten pot that you intend to use for many years, it is wise to use an inner pot, bubble wrap or insulation to create a distance between steel and soil.

Keep in mind that the steel rusts off somewhat in the first two years. If you are worried about stains, you should consider where to place the steel to avoid unwanted discoloration. Feel free to place Corten steel on a stone slab, some of our saucers or the like.

Tips when using Corten indoors

Corten steel is excellent to use indoors and gives a warm and exclusive tone in the home. The Corten welds may pass moisture through if exposed to too much water. There are simple tricks to avoid any rust stains. A simple trick for the pots is to use an inner pot in plastic with an associated plastic saucer to catch any excess water. If you are worried about stains, you should place the steel on, for example, glass, tiles or the like, which is easy to clean if discoloration should occur.

Another alternative is use Matt Lacquer Clear Spray Paint on the rusty Corten to avoid rust stains. By creating a small distance between the bottom of, for example, a pot, you can place them on, for example, a few crowns to get air flow circulation.

Removal of rust stains

There are a number of tricks to remove rust stains from various surfaces. If you get rust on glass, it is easily removed with the help of regular toothpaste, a bit of water and a scrubby. Brush with rotating motions until all rust has dissolved and then rinse off. Baking soda is also effective in removing rust stains. If you have a stone surface, you can sprinkle on baking soda, pour on a little water and leave to dissolve the rust. If you want to clean wood, you can use oxalic acid.

If you have really dark spots on glass or stone, you can sprinkle oxalic acid, pour on some water and let it soak for up to 2 days before rinsing off. For more information see our instructional video.

Tulip monument statue from the Cortenfactory  Corten steel / rust / COR-TEN / Corten / Corten plate

Tips when adding led light to your Corten products

Corten steel is incredibly beautiful to illuminate. It creates an artistic shimmer and gives life to your home even in winter.

Color temperature (Kelvin)

When you are looking for LED lighting products for homes and gardens, people often talk about color temperatures between 2700K and 3000K. Although both are often considered “warm white”, there is a noticeable difference between the two options. 2700K provides a very nice and warm atmosphere and is an excellent choice for living rooms and bedrooms where you want to promote relaxation. 3000K instead gives a purer neutral white color compared to 2700K which in some cases can be perceived as yellow. 3000K is often used in kitchens, laundry, bathrooms and home offices where visual tasks are more common and warmth and relaxation are not the primary goal.

In the picture with our statue Tulip we have used 3000K. That since Corten itself has a brown tone. The color reprocessing will as such be perceived in the warmer direction when directing light towards the Corten steel. Therefore, 3000K is often preferable to 2700 K when lighting the Corten.


Another issue to consider when it comes to lighting is what strength you want on the light. Via the traditional light bulbs this was stated in Watt. Nowadays, people instead talk about the lumen in relation to LED lighting. If you want to add light outdoors at night, when it is naturally completely dark, great contrasts are created when directing light to a specific spot. Then a rule of thumb is not to use too high lumen level as it creates too great contrasts. The ledstrips we offer therefore have 460 lumens (5 watts).

IP classification

Another point to consider is IP classification. This scale indicates how well the lighting equipment is protected from water, dust, intrusive objects and touch. A rating of IP 44, for example, is not waterproof but prevents water from reaching electrical parts. In order for a product to be considered completely waterproof and to withstand prolonged immersion in water, it must have an IP rating of 68.


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