“Corten steel is a half-baked product with many limitations.” Such comments emphasise the popular misconceptions about Corten steel, especially when it comes to outdoor applications. Yet this scepticism is not without merit. When unprotected, Corten steel is indeed particularly vulnerable to rain and runoff. This runoff can carry rust particles onto nearby floors and pavements, leaving unsightly reddish-brown streaks that are difficult to clean. The floor contamination caused by unsealed Corten steel in the image below shows how its natural weathering can lead to unexpected and unwanted consequences.
The Real Problem: Misunderstanding the Corten
The sight of these rusted surfaces may lead one to believe that Corten steel is defective, but in fact, Corten steel is designed to prevent natural corrosion. As a protective mechanism, the surface rust is actually a dense protective film of rust that prevents the corrosion from spreading and progressing inward and protects the substrate underneath the rust layer to slow down its corrosion rate. However, if not handled properly, the rust layer can cause problems. That's why it's important to understand that using this material directly without addressing the runoff problem is only half the solution.
Corten steel is not inherently ‘half-baked’ or limited; the real problem is that it is applied directly without treatment. While the rust layer prevents further corrosion, it does not prevent rust particles from penetrating into the surrounding area.
The Solution: Proper Sealing
To fully utilise the aesthetic and functional potential of Corten steel in outdoor environments, proper sealing is key. BROMOCO's CT7571 Corten Steel Sealer is an effective solution that creates a protective barrier on the surface, preventing water and moisture from penetrating the steel. This stops run-off from causing staining of floors, walls and surrounding surfaces. The sealer allows the steel to retain its signature weathered look while ensuring a clean, stain-free environment. Below is a snapshot of BROMOCO's 25 Hanover Square project with Basha-Franklin Associates. The practice wanted Corten steel paired with Portland limestone to create a unique visual effect, but didn't want the Portland limestone to be stained by the Corten steel. You can clearly see the performance of BROMOCO CT7571 Corten Steel Sealer put to the test in our mock-up.
Using Corten Steel Right
When used correctly, Corten steel is a fantastic material for outdoor applications, including gardens, street utilities, and architectural elements. The key is in understanding how to manage its weathering process to avoid unintended consequences, such as rust stains. Paired with images of what happens when Corten steel is left unprotected, the importance of proper sealing becomes crystal clear.
So back to the original question, is Corten steel really a defective product? The answer is no. It just needs the right techniques and treatments to reach its full potential.
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