Unknown in Quebec 10 years ago, Corten steel is gradually becoming more comfortable in landscaping to which it adds a unique character with its natural patina: raw, alive, constantly evolving. This second skin acts as a shield that gives the material exceptional longevity and resistance.

Despite a rusty metal appearance, Corten steel is particularly resistant to corrosion. Rust invites itself to it only on the surface, which protects it and gives it that rustic appearance that many are looking for, without, however, its integrity being altered. Reserved until now for works of art, commercial projects and high-end residences, it is gradually being extended to a wider clientele who appreciate its contemporary look and easy maintenance.

It then gains a variegated patina in more or less dark earth tones. This color can also be obtained with a solution of vinegar, water and peroxide, which will cause it to rust within an hour. The color of Corten steel stabilizes after 12 to 18 months and then evolves more slowly. Over the years, the Corten will adopt shades of a deeper brown, almost black.

Making this choice amounts to opting for a certain durability, considers landscape architect Jocelyn Lussier, of Topia. “Corten steel lasts a long time and requires no maintenance. Aesthetically, it is a beautiful complement to the greenery with its ocher, brown and orange hues. It also offers us great latitude in terms of creativity, especially if we have it custom-made. With a beautiful play of light, the effect in the garden is striking. »

In exterior landscaping, it is found as a basic material in a panoply of objects – fireplaces, fences, fountains, light fixtures, planters and decorative screens – but also as borders for steps or flowerbeds to which it gives a graphic side, in addition to a solidity. “It has this particularity of blending into the environment while having a strong presence. The result is very natural, very organic,” argues landscaper Dominique Filion.

Its raw look goes particularly well with contemporary or mid-century style environments. It will blend well with concrete, stone, wood and other rough materials.

Once the “ideal” shade has been achieved, the aging process can be interrupted by applying varnish. As Corten does not like bathing in water, this protective layer will sometimes be applied to accessories such as fountains, to protect it. Some products are also sold pre-painted, “but the beauty of the material is precisely that it requires no maintenance and that it continues to acquire a patina and evolve over time”, emphasizes Jocelyn Lussier. While Corten steel is four times stronger than standard steel, it becomes 15 times stronger when painted, says Yan Grand Maison, whose company, Corrolux, specializes in in Corten steel. In this case, however, it will be necessary to plan to repaint regularly.

The difficulty of finding this material in Quebec and the desire to embark on the movement to upgrade outdoor environments convinced entrepreneur Isabelle Quintin to make Corten steel her specialty. “We choose it for more than a lifetime since it easily lasts more than 50 years. It is ultra-resistant, but it also has the advantage of being 100% recyclable or reusable if you change your mind. »

It’s not so much the Corten that will eventually yield over time, according to her. Rather, the damage will be caused by poorer quality craftsmanship and assembly. “If you choose an accessory that has been assembled with screws, for example, the quality could be compromised over the years. This is the reason why I only offer welded products. »

The thickness, which oscillates between 1.5 and 6 mm, for an average of 2 to 3 mm at the two suppliers that we contacted, is also an index of quality, but it all depends on the use that will be made of the material: the thicker it is, the stronger it is; thinner, and therefore more flexible, the material will adopt curves more easily. On the price side, it remains an expensive choice, more expensive than standard steel, but less than stainless steel. In the case of a retaining wall, the costs can be compared to that of stone, but it has the advantage of being easier to install. If we evaluate its longevity and its uniqueness, it is a choice that pays off in the long term, argues Isabelle Quintin. “A Corten steel planter might be three times more expensive than one made of plastic or wood, but it will last quite a bit longer. »

In 1933, the American company United States Steel Corporation patented its invention, in full swing of research to develop new steels. Cor-ten, or CorTen, was then a success with manufacturers of railway equipment. The alloy of copper, chromium, nickel and phosphorus is not only lighter than ordinary steels, it is also more resistant to shocks and corrosion. From the middle of the century, it will begin to make its appearance in architecture that claims to be “avant-garde”. Its weather resistance will make it a material of choice for exterior cladding and garden layouts.