Corten Steel – Genus Triangular Raised Bed Planter

Starting out as a blue steel, as soon as Corten Steel is exposed to the elements it will naturally weather and develop a rich eye-catching finish. This natural fixed coating of rust provides protection against further corrosion. During the weathering process the Corten Steel produces carbon run off which can stain adjacent materials such as stone or concrete. To reduce this possible staining, all Corten Steel products have small feet, lifting the product and preventing direct contact with the flooring material. After the initial reactive period Corten Steel will cure and self-seal with little to no carbon run off. Standard material thickness is 2mm and we offer a made to measure service as well as our wide range of sizes of boxes, cylinders and troughs.

Corten Steel

Corten Steel, also known as weathering steel, is a special steel originally developed for bridge building and skyscraper construction due to its incredible strength. It starts out as a blue steel but on exposure to the elements, develops a protective, striking rust appearance, creating warm rich textures not always associated with metal. Due to the chemical composition of Corten Steel, a very dense oxidisation layer is formed during the weathering process which protects the blue steel inside. This natural fixed coating of rust provides protection against further corrosion. If this protective barrier is compromised, it will simply form a new skin to protect itself. Corten Steel is extremely durable and has a far higher resistance to atmospheric corrosion than other steels.

Run Off
During the weathering process the Corten Steel produces carbon run off or staining to adjacent materials such as stone or concrete. To reduce this possible staining, we recommend raising the product up off the ground by using a suitable stand, blocks of wood, slabs and such like; this will prevent any direct contact with the flooring material. After the initial reactive period Corten Steel will cure and self-seal with little to no carbon run off. The weathering process of Corten Steel is integral to this product and as such we will not accept any responsibility for damage caused to surrounding materials as a result of carbon run off from Corten Steel products. Please ensure you do not place your product on any surface that may be damaged during the weathering process.

Step-by-Step Weathering Guide

• Stage 1 – Freshly manufactured Corten Steel. At this stage the dark oily residue coats the Corten Steel.
• Stage 2 – The oily residue is beginning to break down, as the Corten Steel begins to weather.
• Stage 3 & 4 – The “Run-Off” stage – This can take around 3-9 months depending on weather and positioning.
• Stage 5 & 6 – The final stages of the weathering process. Some “Run-Off” may still occur as the Corten Steels patina develops to a striking, more consistent appearance.

Corten can be easily cleaned using water and a soft brush. it can be sealed using a metal specific varnish, please note this will make the steel appear ‘wet’ or darker for the rest of the item’s life.

If Corten Steel is scratched or the weathered surface is damaged, it will re-weather (heal) itself back to the original weathered state, making the damaged area nearly undisguisable from the rest of the planter.

The Initial Weathering Process

Upon receiving your corten steel garden feature, it will likely appear unweathered with a dark, oily residue. This is the first stage of the weathering process, which protects the steel during transportation and initial setup. 

Place the corten garden feature outdoors in an open area where it can be exposed to the elements. The weathering process, where the steel forms a protective rust layer, typically takes between 3 to 9 months, depending on weather conditions. 

During the weathering period, avoid placing the feature on or near porous surfaces like stone or concrete to prevent staining from rust runoff.

Guidance on Sealing and Maintenance

Once the desired rust patina has developed, sealing the surface with paint conditioning and rust inhibitor oil is recommended to stabilise the rust layer and minimise further runoff. 

Our sealing oil recommendation: Owatrol Oil

This product penetrates through the rust to the sound metal below, isolating and protecting it from additional corrosion. You can apply Owatrol Oil using a brush or sprayer and allow it to dry for 12 hours, with a full cure taking up to 48 hours, depending on environmental conditions. This treatment not only enhances the durability of your corten steel garden feature but also maintains the integrity of its rustic appearance.

By following these simple steps, your corten garden feature will achieve a beautifully weathered look while being well-protected for years of enjoyment in your garden.