Corten Vs Galvanised steel – What is the difference?

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Corten Vs Galvanised Steel

Designing the perfect outdoor space, whether it’s for a residential or commercial property, demands the use of the right materials. Steel, with its strength, durability, and aesthetics, stands out as a superb option. However, the choice between Corten Steel and Galvanised Steel can be challenging. Both offer unique benefits and aesthetics, significantly impacting the final result of your landscaping project.

In this post, we’ll delve into the unique characteristics and differences between Corten and Galvanised Steel, addressing key factors for consideration. Helping you make an informed decision and select the best material to bring your outdoor vision to life.

What is Corten Steel?

Corten steel which is commonly known as weathering steel is a high-strength, low-alloy steel originally developed to eliminate the need for painting.  Corten offers many benefits and is popularly used to create outdoor sculptures including the Angel of the North and large constructions such as bridges due to its incredible properties. The name COR-TEN refers to the two distinguishing properties of this type of steel: corrosion resistance and tensile strength.

Nowadays, it is commonly used in the architectural and landscape industries thanks to its beautiful finish that develops when exposed to the elements and low maintenance requirements. To learn more about Corten check out our What is Corten Steel? blog post.

What is Galvanised Steel?

Galvanised steel is a result of a unique process called hot-dip galvanising. The process involves coating steel with a layer of zinc by immersing the steel in a bath of molten zinc at a temperature of around 450 °C. During the process, a metallurgically bonded coating is formed which protects the steel internally and externally against corrosion.

The material’s excellent durability and low maintenance requirements make it a common choice for outdoor applications such as Galvanised Planters, Gates, Fencing, Railings and Street Lamps.

So, what is the difference?

Both Galvanised Steel and Corten Steel can provide a huge array of benefits to users, but there are a few key differences between the two:

  • Appearance

Corten Steel begins its life in a deep bluish hue. As it undergoes the weathering process, a captivating transformation occurs. In the early stages, usually, within a few weeks to months, Corten develops a bright orange patina. As time progresses, typically over 6 to 9 months, this colour deepens to a darker, rich brown, giving the material an earthy, natural aesthetic that blends seamlessly into most garden environments.

On the other hand, Galvanised Steel offers an entirely different visual appeal. It starts as a bright, shiny metallic silver-grey, highlighted by a distinctive crystalline, snowflake-like pattern. This unique pattern is the outcome of the hot-dip galvanising process, adding a level of texture and complexity to the material’s appearance. As it weathers over time, Galvanised Steel transitions into a more subdued, matt-grey colour. This muted finish provides a contemporary, clean aesthetic that can beautifully complement various outdoor design styles.

  • Corrosion

One of the most notable properties of Corten Steel is its exceptional corrosion resistance. With time, Corten develops a unique, rust-like patina on its surface. But don’t let the rust-like appearance fool you; this layer isn’t a sign of degradation but rather a protective barrier. It safeguards the inner steel from further corrosion, contributing significantly to Corten’s durability and lifespan. Thanks to this protective layer, Corten Steel products stand up to the elements for an extended period, making them an excellent investment for your outdoor space.

Galvanised Steel also possesses impressive anti-corrosion properties, although it achieves this through a different process. During the hot-dip galvanising phase, the steel is coated with a thin layer of zinc, which creates a protective barrier against rust and corrosion. This zinc coating ensures that Galvanised Steel remains tough and durable, resisting the wear and tear of environmental exposure with ease.

 The durability of both Corten and Galvanised Steel is heavily influenced by location and environmental factors. However, one thing is certain: these materials are built to last. Whether you opt for the rustic charm of Corten Steel or the industrial appeal of Galvanised Steel, you can rest assured that your chosen material will serve you well for many decades.

  • Composition

 At its core, Corten Steel is an alloy steel, primarily composed of iron and carbon. What sets Corten apart, however, are the additional alloying elements it incorporates. Chromium, nickel, copper, and phosphorous are among these added elements, and they play a vital role in giving Corten Steel its unique self-protecting characteristics. 

Galvanised Steel is typically mild steel before undergoing the galvanisation process and the key components of mild steel are mainly iron with a small amount of carbon.

  • Cost 

When it comes to cost, there is often a misconception that Corten Steel products are significantly more expensive. While corten garden products do tend to be around 50% more costly on average than mild steel products, this doesn’t tell the whole story. The galvanising process, applied to mild steel to create Galvanised Steel, incurs additional expenses and involves extra work. Once these factors are considered, the cost difference between Corten and Galvanised Steel products narrows considerably.

  • Sustainability 

Corten Steel stands out not only for its durability and aesthetic appeal but also for its impressive environmental credentials. Being 100% recyclable, Corten Steel is a truly sustainable choice. Furthermore, the natural weathering process eliminates the need for additional painting or coatings that may involve potentially harmful chemicals. This inherent resistance to the elements also ensures the material’s longevity, which means fewer replacements and less overall material consumption.

Galvanised Steel also exhibits commendable sustainability attributes. It is easily recyclable and notably durable, which leads to fewer replacements over its lifespan.

Both Corten Steel and Galvanised Steel contribute towards a circular economy. This economic system aims to minimise waste and optimise resource use. Materials like Corten and Galvanised Steel are in line with this philosophy, as their recyclability and durability ensure they are kept in use for as long as possible.

Choosing between Corten and Galvanised Steel

When it comes to choosing between Corten and Galvanised Steel, the materials offer many similarities including excellent longevity and low maintenance benefits, making them highly favourable choices for a wide range of projects. So, the deciding factor largely comes down to the aesthetics and design vision you’re looking to achieve.