Why RB73 Uses Corten Steel in Every Outdoor Fire and Kitchen

What Is CorTen Steel (And Why It’s Not Just “Rusty Steel”)

Let’s clear something up straight away — not everything that rusts is CorTen.

CorTen steel (also known as weathering steel) is a specific engineered alloy, not just untreated mild steel left outside to rot. The name itself tells you what it’s built for:

  • COR – corrosion resistance
  • TEN – tensile strength

 

Originally developed by U.S. Steel, CorTen is made by adding elements like copper, chromium, nickel, and silicon to iron.

This is what allows it to do something ordinary steel can’t…

It rusts… and then stops.

Instead of continuous corrosion, CorTen develops a stable outer layer (called a patina) that protects the steel beneath from oxygen and moisture.

So that rich orange-brown finish?
That’s not damage — that’s armour.

The RB73 Difference: Thickness Matters More Than You Think

Here’s where things get interesting — and where most products quietly cut corners.

At RB73, we use:

  • 3mm CorTen steel for all fires and outdoor kitchens
  • 2mm CorTen steel for pipes and logstores

 

That thickness isn’t random. It’s deliberate.

Why? Because:

  • Thicker steel = slower oxidation penetration
  • Thicker steel = greater structural strength under heat
  • Thicker steel = longer lifespan outdoors

 

In real-world terms, this means our products are built to sit outside in British weather — rain, frost, the occasional sideways storm — without falling apart after a few seasons.

Now, here’s the uncomfortable truth…

If a product looks similar but costs significantly less, there’s usually a reason.
And it’s rarely because the manufacturer is feeling generous.

We don’t know exactly what thickness others use — but thinner steel is cheaper, lighter, and… less durable. Draw your own conclusions.

Not All “Weathering Steel” Is Genuine CorTen

You’ll often see terms like:

  • “Weathering steel”
  • “CorTen style”
  • “Rust finish steel”
  • “Rusted steel”

 

Translation? It might not be CorTen at all.

Genuine CorTen is a controlled alloy with specific properties.
Imitations often lack the right composition, meaning:

  • The rust layer doesn’t stabilise
  • Corrosion continues deeper into the steel
  • Lifespan drops dramatically

 

It’s the difference between a material designed to age gracefully…
and one that just slowly eats itself.

RB73 uses genuine CorTen steel because it forms a protective rust layer that prevents further corrosion, delivering exceptional durability. Combined with our use of 3mm thick steel for fires and kitchens and 2mm for pipes and logstores, this ensures long-term performance outdoors, even when left uncovered year-round.

Sourced Properly: Why Our Steel Comes from Sweden

Not all CorTen is created equal either.

We source our steel from a specialist factory in Sweden — one of the few places globally producing true, high-grade CorTen steel.

That matters because:

  • Consistent alloy composition = predictable performance
  • Higher-quality production = better patina formation
  • Fewer impurities = longer-lasting protection

 

In short, it ensures the material behaves exactly how it should — not how you hope it will.

How CorTen Performs in the Real World

CorTen steel doesn’t just look good — it earns its place in your garden.

What to Expect:

  • Rust development (2–6 months) – The protective layer forms naturally over time depending on weather conditions.
  • Initial runoff – Early-stage rust can leave marks on patios or tiles — completely normal, and temporary.
  • Zero maintenance – No painting, no sealing, no covering required.
  • Decades of use – CorTen can last up to 10x longer than ordinary steel when used correctly.

Can You Speed Up the Rusting Process?

Yes — if you’re impatient (no judgement). While all of our outdoor woodburners and outdoor kitchens are supplied pre-rusted, our logstores typically come un-rusted, you can accelerate the patina on these products using a simple solution:

  • Water + table salt
  • Water + vinegar
  • Specialist acid solutions

 

Spray it on evenly to kickstart the oxidation process and create a more uniform finish early on.

Are you buying something for this summer… or the next 15 summers?

Why RB73 Chooses CorTen (And Won’t Compromise)

We don’t only use CorTen because it looks good (though it does).
We use it because it performs.

Combined with our chosen thicknesses, it delivers:

  • Long-term durability in real outdoor conditions
  • Structural strength under repeated heat cycles
  • A finish that improves with age, not deteriorates
  • A product you can leave outside year-round without worry

 

Could we make things cheaper?
Of course.

Would they last as long?
Not a chance.

Even going from 3mm thick to 2mm thick reduces the steel thickness by 33%. Which on our outdoor woodburners would dramatically reduce their lifespan. The cost is therefore a false economy as while the unit might be cheaper, if you have to replace it every 5 years it will cost you more in the long run.

Final Thoughts: Built to Last, Not Just to Sell

There’s a big difference between a product that looks the part on day one…
and one that still delivers years down the line.

CorTen steel — when it’s genuine, and when it’s used properly — is one of the best materials available for outdoor fires and kitchens.

Add in the right thickness, the right sourcing, and the right design…
and you get something that doesn’t just survive outdoors – it belongs there.

And here’s the funny part…
Built properly, a CorTen product like this won’t just last your time with it — it’ll likely still be standing long after.

Don’t be surprised if it ends up being the one thing your kids argue over in the will.

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