Ask around the South African building industry about anodised aluminium and you will often hear the same two verdicts: it is outdated, it does not last, it’s not available. All are wrong! Where anodising has disappointed in this market, the cause was never the finish itself. It was the quality of the process behind it.
At Reynaers Aluminium, we believe South African architects and homeowners deserve the full picture. So here is an expert view on what anodising is, where it outperforms, where it falls short, and why it remains one of the most durable finishes – available in South Africa – for aggressive coastal environments.
What anodising actually is:
Powder coating applies a layer of paint on top of the aluminium. Anodising does something fundamentally different: it grows the finish out of the metal itself.
In a controlled electrochemical bath, the surface of the aluminium profile is converted into a hard, dense layer of aluminium oxide. This is the same protective oxide aluminium forms naturally, only thicker, harder and far more uniform. The layer can then be coloured and, critically, sealed, closing its microscopic pores to lock out moisture and salts.
The result is not a coating that sits on the surface. It is the surface. That single difference explains most of anodising’s strengths, and most of its limitations.
Why anodising is rare in South Africa, and how Reynaers does it differently
If anodising performs so well, why is it so uncommon here? The honest answer: very few suppliers can deliver it to a standard they are willing to guarantee. Consistent anodising demands tightly controlled chemistry, precise thickness, verified sealing and colour matching across every batch. Without that control, offering a long-term guarantee on an anodised finish in a coastal market is simply too great a risk. So most suppliers purposefully steer clients towards powder coating instead.
Reynaers takes a different approach. They anodise their our own aluminium through Alural, the Reynaers Group’s in-house surface-treatment facility. That gives Reynaers direct control over every stage that determines long-term performance:
- Process control: bath chemistry, oxide thickness and sealing are managed by own specialists, not outsourced.
- Colour consistency: one controlled source means matched tones across an entire project, from the first profile to the last.
- Quality assurance: finishes are tested against recognised European quality standards before they leave the facility.
- Guarantee confidence: because they control the process end to end, we can stand behind the finish with a long-term guarantee.
In short, anodised aluminium can be offered in South Africa, with confidence and with a guarantee. It simply requires a supplier who owns the process.
The Pros and Cons, Honestly weighed
No finish is right for every project.
| Anodised aluminium | |
|---|---|
| Pro: integral finish | Cannot peel, flake, blister or delaminate, because there is no separate layer to lift. |
| Pro: hardness | Aluminium oxide is exceptionally hard, giving strong resistance to abrasion and wind-blown sand. |
| Pro: UV stability | Colour is held within the oxide layer, so it resists chalking and fading under intense South African sun. |
| Pro: metallic character | Retains the depth and natural sheen of the metal, which paint can only imitate. |
| Pro: sustainability | No paint layer to strip, so profiles recycle cleanly at end of life. |
| Con: narrower palette | Largely limited to natural silver, champagne, bronze, black and stainless-steel tones. |
| Con: batch variation | Metallic tones can vary slightly between production runs, so large projects need a single controlled source. Reynaers will always supply two colour shades within which the anodised difference is acceptable |
| Con: harder to repair on site | Deep scratches cannot simply be touched up; damage must be avoided during installation. |
| Con: sensitive to alkalis | Wet cement, mortar and harsh alkaline cleaners can mark the surface, so protection on site matters. |
| Con: process-dependent | Performance depends entirely on layer thickness and sealing quality. A poor anodiser produces a poor finish. |
That last point is the one that matters most in South Africa, and we return to it below.
Anodising in Corrosive and Coastal Environments
South Africa has close to 3,000 km of coastline, and much of our premium residential and hospitality work sits within a few hundred metres of the sea. Salt-laden air, high humidity and strong winds make this one of the toughest tests any façade finish can face.
Here, anodising has a structural advantage. The most common failure mode of painted aluminium at the coast is filiform corrosion: fine, thread-like corrosion that creeps beneath the paint film from a cut edge or scratch, lifting the coating as it goes. Because an anodised finish is part of the metal, there is no film for corrosion to travel under.
But that advantage only holds when three conditions are met:
- Sufficient layer thickness. Internationally, a minimum average oxide thickness of 20 microns is the benchmark for exterior use, with 25 microns recommended for aggressive marine and industrial exposure.
- Proper sealing. An unsealed or poorly sealed layer stays porous, allowing chlorides in. Sealing quality is tested and should be certified.
- Certified process control. Independent quality labels such as Qualanod audit bath chemistry, thickness and sealing on an ongoing basis.
Maintenance is simple but not optional. In coastal zones, rinsing profiles with fresh water and a pH-neutral cleaner every three to six months removes salt deposits before they can attack the surface. This applies to every aluminium finish, anodised or powder coated.
Specified correctly and produced to that standard, anodised aluminium is one of the best-performing finishes available for the South African coastline.
Myth-busting: “Out of Trend”; “Lesser Quality” or “Not Available”
Myth 1: Anodised aluminium is out of fashion.
The opposite is true internationally. Across Europe, anodised bronze, champagne and deep black finishes are specified on some of the most design-led residential and commercial projects being built today. Architects choose them precisely because they offer an authentic metallic depth that complements natural stone, timber and concrete. The dated image many South Africans hold comes from the flat, patchy silver frames of decades past, not from what modern anodising can achieve.
Myth 2: Anodised aluminium is lower quality than powder coating.
Anodised aluminium is not inherently better or worse than powder coating. It is different, and in several respects, harder-wearing. What varies enormously is the quality of the anodiser. A thin, poorly sealed layer will stain, pit and degrade quickly at the coast. A certified, correctly sealed layer of the right thickness will perform for decades.
The reputation problem in South Africa is a supplier problem, not a finish problem.
Anodised vs powder coated: choosing the right finish
The right choice depends on the design intent, the exposure and the maintenance plan.
| Criterion | Anodised | Powder coated |
|---|---|---|
| How it works | Oxide layer grown from the metal | Polyester paint layer fused onto the metal |
| Look | Authentic metallic depth | Solid, metallic, textured or special-effect finishes |
| Colour range | Focused metallic palette | Hundreds of RAL colours plus textures |
| Coastal risk | No film to lift; filiform corrosion not a factor | Needs marine-grade pre-treatment and coastal-class powder |
| Scratch resistance | Very high | Good |
| On-site repair | Difficult | Touch-up possible |
| Best suited to | Design-led coastal homes, hospitality, heritage and contemporary metallic aesthetics | Projects needing a specific colour or texture match |
Frequently asked questions (FAQ’s)
Does anodised aluminium corrode near the sea? A properly sealed anodised layer of at least 20–25 microns is highly resistant to coastal corrosion. Regular freshwater rinsing keeps salt deposits from building up.
Is anodised aluminium better than powder coating? Neither is universally better. Anodising offers superior hardness and a finish that cannot peel. Powder coating offers a far wider colour and texture range. Your exposure and design intent should guide the choice.
Can anodised aluminium be guaranteed in South Africa? Yes, when the supplier controls the process. Reynaers anodises its own aluminium through it’s Alural facility, which allows us to guarantee the finish long term.
What colours does anodised aluminium come in? Typically natural silver, champagne, bronze tones, black and stainless-steel effects. Reynaers can advise on the full range available.
How do I maintain an anodised finish? Rinse with fresh water and clean with a pH-neutral detergent and soft cloth every three to six months in coastal areas. Avoid abrasive pads and alkaline cleaners.
Talk to Reynaers Aluminium in South Africa
See the difference for yourself. Book a visit to the Reynaers Haus showroom in Cape Town to compare our extensive range of anodised and powder-coated finishes side by side, or speak to our team about the right finish for your next coastal project. [Book a showroom visit] · [Request finish samples]
As ever, it’s always recommended to do your research, compare products and consult with experts to help you make an informed decision that the best meets your design and budget needs. Connect in South Africa with a local Reynaers representative here
