Aluminium: The Versatile Metal
The Wood Guide · Materials
MaterialAluminium
The third most common element in the Earth's crust, once more precious than gold. Today it is in aircraft, drinks cans and garden furniture — and that is no coincidence.
- Light and corrosion-resistant
- Endlessly recyclable
- Extraction uses a lot of electricity
Aluminium
The third most common element in the Earth's crust, once more precious than gold. Today it is in aircraft, drinks cans and garden furniture — and that is no coincidence.
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Why aluminium is everywhere
One metal that is light, does not rust, conducts well and is easy to shape — that combination is rare.
At around eight per cent of the Earth's crust, aluminium is the most common metal on Earth, but it never occurs in pure form. It is locked up in bauxite, and that is exactly why it was only isolated for the first time in the nineteenth century. Until then it was more precious than gold: Napoleon III had his most important guests eat from aluminium tableware while the rest had to make do with silver.
In 1886 the Hall–Héroult process changed everything. By dissolving aluminium oxide in molten cryolite and passing a current through it, large-scale production became possible. Within a few decades the price fell from precious metal to everyday metal, and that is why you find it today in a can of fizzy drink.
In the garden, aluminium is mainly used for frames, legs and bases. It does not rust, it weighs little and it can be pressed into any shape. For a table you move often, that is a real advantage.
Within seconds, aluminium forms a thin, hard oxide layer that shields the metal underneath. Anodising deliberately makes that layer thicker and harder. That is why aluminium does not rust away outdoors like steel — it protects itself.
- Symbol and atomic number
- Al · 13
- Specific gravity
- about a third of steel
- Corrosion
- forms its own protective oxide layer
- Forming
- easy to roll, press and extrude
- Recycling
- endless, without loss of quality
- Energy for recycling
- a fraction of that for new aluminium
- In the garden
- frames, bases, parasol bases
To be fair: extracting new aluminium is one of the most electricity-hungry industrial processes there is: the metal literally has to be separated out with electricity. Recycling needs only a fraction of that, but that does not suddenly give new aluminium a light footprint. And in the garden: an aluminium tabletop gets hot in the sun, and a light piece of furniture blows over.
Five properties that together make the difference
| Property | What it gives you | Where you see it |
|---|---|---|
| Light weight | about a third of steel for comparable stiffness | aircraft fuselages, bicycle frames, movable tables |
| Corrosion-resistant | protects itself with an oxide layer | window frames, facade panels, garden furniture |
| Good conductor | carries electricity and heat away efficiently | high-voltage cables, heat sinks in electronics |
| Easy to form | can be rolled into foil or pressed into profiles | aluminium foil, window profiles, bases |
| Recyclable | remelts without loss of quality | drinks cans, scrap that becomes profile again |
A hundred years of falling prices
In the decades after it was first isolated in 1825, aluminium was a curiosity for monarchs and exhibitions. The tip of the Washington Monument was finished with it in 1884 — a pyramid of less than three kilos, at the time as expensive as silver.
The Hall–Héroult process of 1886 made mass production possible, and the twentieth century did the rest. The metal made aviation possible and later space travel: from the Apollo modules to the hull of the International Space Station, aluminium alloy is the material strong enough to carry loads and light enough to launch.
From facade to drinks can
Construction
Window frames, facade panels, roofing and garden furniture. Anywhere something stands outdoors and must not rust.
Transport
Aircraft fuselages, car parts, bicycle frames and ship superstructures. Every kilo less is fuel saved.
Packaging
Cans, foil and food packaging. This is where recyclability matters most.
Electronics
Casings and heat sinks — the metal carries heat away quickly and is light enough to carry around.
Aluminium or wood for outdoor furniture?
We make garden furniture in wood, and we have also sold aluminium picnic tables. The honest comparison is below.
Light and low-maintenance
The choice when the furniture often has to be moved or stored away.
- Does not rust, needs no oiling
- Light: one person can move a table
- Top gets hot in full sun
- Blows over more easily in a storm
- A scratch in the coating starts to corrode
Heavy and warm
The choice when the furniture stays put and has to last for years.
- Pleasant to the touch, even in the sun
- Stays put in the wind — precisely because of its weight
- Turns grey; maintenance is a choice, not an obligation
- Damage can be repaired
- Heavy to move
On a balcony or roof terrace where everything must be light and movable, aluminium wins. On a patio, in a garden or in a public space, where a table stands in the same spot for years and has to withstand heavy use, solid wood wins — and that is exactly why our KING tables are made of spruce.
The energy side of aluminium
Making new aluminium is electrolysis: a large amount of electricity passes through it to separate the metal from oxygen. As a result, the footprint of primary aluminium depends heavily on how that electricity is generated — hydropower in Norway or coal elsewhere makes a world of difference.
The flip side is just as real: remelting takes only a fraction of that energy, and aluminium loses no quality in recycling. A can can go on being a can for ever. That makes the recycling rate the most important figure for this material — more important than the material itself.
Frequently asked questions about aluminium
Does aluminium rust?
No. Rust is specific to iron. Aluminium does oxidise, but that immediately forms a thin protective layer that seals off the metal underneath — so it does not keep attacking itself.
Why was aluminium once more expensive than gold?
Because it never occurs in pure form and there was no practical process to extract it. Only with the Hall–Héroult process of 1886 did large-scale production become possible, after which the price collapsed.
Is aluminium garden furniture better than wooden furniture?
Different. Aluminium is light and needs little maintenance, but it gets hot in the sun and blows over more easily. Solid wood stays put, feels more pleasant and can be repaired, but it is heavy.
Can aluminium be recycled endlessly?
In principle, yes, without loss of quality. That is the material's main environmental advantage: remelting takes a fraction of the energy that new aluminium requires.
What is anodised aluminium?
Aluminium whose natural oxide layer has been thickened and hardened electrochemically. That makes the surface more hard-wearing and allows it to be coloured.
Do you sell aluminium garden furniture?
Not at the moment — our range is solid wood. We have stocked aluminium picnic tables in the past, so it is not ruled out.
Still prefer wood?
Our tables and benches are made of solid spruce or hardwood. Heavier, warmer, and still repairable after twenty years.
Have a question about your project? Just ask — we're happy to help.
Photos via Wikimedia Commons: Bauxite, the ore from which aluminium is extracted — Martina Grosty, CC BY 3.0 · Lend, Salzburg — Wald1siedel, CC BY-SA 3.0 · Lend, Salzburg — Wald1siedel, CC BY-SA 4.0