Anodising vs powder coating aluminium: which finish to choose
Anodising and powder coating are the two main finishes for aluminium, and the choice comes down to appearance, durability and environment. Anodising thickens the metal’s own oxide layer for a hard, integral, UV-stable finish in metallic tones, to EN 12373 (Qualanod). Powder coating bakes on a thick coloured polymer film in the full RAL range, to EN 12206 (Qualicoat). This guide compares the two on process, thickness, colour, durability and coastal performance, so you can specify the right one.
Why aluminium is finished
Aluminium already resists corrosion through a thin natural oxide layer, so a finish is applied for two reasons: appearance and extra protection. A finish gives colour, a consistent surface and added durability in harsh or coastal environments, and it protects the metal where the natural oxide alone is not enough. Both anodising and powder coating build on the aluminium substrate covered in our guides to EN AW aluminium alloys and aluminium profiles, and both are far more durable than paint. For the corrosion behaviour of bare aluminium, see our guide to whether aluminium corrodes.
What anodising is
Anodising is an electrochemical process that thickens the aluminium’s natural oxide layer under controlled conditions, growing a hard, dense oxide that is an integral part of the metal rather than a coating on top. Because the oxide is grown from the metal, it does not chip, flake or peel, and it is exceptionally hard and abrasion resistant. Architectural anodising to EN 12373 gives a layer of about 15 to 25 microns, and the Qualanod label sets a minimum of 15 microns for exterior use and 20 microns for coastal or industrial exposure, designated by class such as AA20. The finish is UV stable, so it does not chalk or fade.
What powder coating is
Powder coating sprays a dry polymer powder, usually a polyester, onto the cleaned and pre-treated aluminium by electrostatic charge, then bakes it in an oven so it melts and cures into a solid coloured film. It is a coating on the surface, typically 60 to 120 microns thick, giving a much thicker barrier than anodising. Architectural powder coating to EN 12206 carries the Qualicoat label, with durability classes: Class 1 for standard architectural use, Class 2 super-durable and Class 3 ultra-durable, and a Seaside qualification for coastal environments. The full RAL colour range is available in matt, gloss, textured and even wood-effect finishes.
Head to head
| Property | Anodising | Powder coating |
|---|---|---|
| Nature | Integral oxide grown from the metal | Polymer film applied on the surface |
| Standard / label | EN 12373 / Qualanod | EN 12206 / Qualicoat |
| Thickness | About 15 to 25 microns | About 60 to 120 microns |
| Colour range | Metallic tones: silver, bronze, black, gold | Full RAL, matt, gloss, textured, wood-effect |
| Chipping | Cannot chip or peel, part of the metal | Can chip if the film is cut or struck |
| Abrasion and UV | Very hard, UV stable, will not fade | Good, super-durable classes resist fade |
| Coastal | Good at 20 microns or more | Excellent with Seaside qualification |
Colour and appearance
Colour is often the deciding factor. Anodising keeps a metallic look, the natural aluminium tone or a dyed bronze, black or gold, with the grain of the metal still visible, which suits architectural and premium products. Powder coating covers the metal in a solid colour from the full RAL palette, in matt, gloss, satin or textured finishes, so it matches any colour scheme, including the RAL 7016 and RAL 9005 shades common on aluminium fencing. If the design needs a specific colour, powder coating wins; if it needs a bright or bronzed metallic look, anodising wins.
Durability and environment
Both finishes outlast paint, but they fail in different ways. Anodising is harder and more abrasion resistant, and because it is part of the metal it cannot chip, so it suits high-traffic surfaces, handrails and products that are handled. Powder coating gives a thicker barrier and, with Class 2 or 3 and the Seaside qualification, excellent resistance to chloride corrosion, so it is often preferred in coastal and marine settings. Its one weakness is that a deep scratch through the film can let moisture under the coating, whereas an anodised surface has no film to breach.
Cost and lead time
Cost depends on the part, the colour and the volume, so neither finish is always cheaper. Powder coating is usually economical for coloured parts and short runs and offers the widest colour choice for the price. Anodising can be more economical at volume for metallic finishes and gives the hardest, longest-lasting surface. Both add a processing step and a lead time to bare aluminium, so the finish is agreed at the order stage. Give the finish, the colour or class and the environment with your enquiry so the quotation covers the complete, finished part.
Pre-treatment and preparation
Both finishes depend on clean, correctly prepared aluminium, and the preparation is where quality is won or lost. Before anodising, the aluminium is cleaned, etched and de-smutted so the oxide grows evenly and takes dye consistently. Before powder coating, the surface is cleaned, etched and given a conversion coating, either a chromate or a chrome-free pre-treatment, so the powder bonds and resists corrosion creep from any scratch. The Qualicoat and Qualanod specifications set the pre-treatment as strictly as the finish itself, which is why a labelled applicator gives a more reliable result than an uncontrolled coating. Poor pre-treatment, not the finish, is the usual cause of early failure.
Cleaning a finished surface
Both finishes are low maintenance and last longer with periodic cleaning. Wash the surface with water and a mild, pH-neutral detergent, rinse and dry, and avoid abrasive pads and aggressive solvents that can dull anodising or scratch a powder coat. In coastal or industrial areas, more frequent washing removes the chloride and grime that would otherwise attack any finish over time. Regular cleaning also preserves the appearance, keeping an anodised surface bright and a powder-coated colour true. No repainting is needed, which is a large part of why both finishes are chosen over paint.
Which finish to choose
Choose anodising for a hard, metallic, abrasion-resistant finish that cannot chip, for handrails, architectural profiles, premium products and high-wear surfaces, at 20 microns or more near the coast. Choose powder coating for a specific RAL colour, a textured or matt finish, or the best coastal corrosion barrier, for fencing, facades, gates and coloured products, specifying Class 2 or 3 and Seaside for harsh environments. For a hidden or dry part, mill-finish aluminium may need no coating at all. When in doubt, powder coating covers the widest range of colours and environments, and anodising delivers the hardest and most enduring metallic surface.
Finished aluminium from ULAMEX
ULAMEX has supplied aluminium since 1988, in mill finish and powder coated to order.
| What you get | Detail |
|---|---|
| Products | Aluminium profiles, sheet and fencing systems |
| Finishes | Mill and powder coated to EN 12206 (Qualicoat), to order |
| Colour | The full RAL powder range in matt, gloss and textured |
| Advice | Finish selection for colour, durability and environment, including when anodising is the better route |
| Terms | No minimum order on stocked SKUs, dispatch 2 to 7 working days plus finishing lead time |
Not sure which finish your project needs? Tell ULAMEX the product, the colour and the environment, and the desk will advise and return a non-binding quotation. See our guides to aluminium profiles and aluminium alloys, and our supply capabilities, or contact the export desk at [email protected] or +48 504 424 761.
Frequently asked questions
Is anodising or powder coating more durable?
They are durable in different ways. Anodising is harder and more abrasion resistant and cannot chip because it is part of the metal. Powder coating gives a thicker barrier and, with a super-durable class and Seaside qualification, excellent coastal corrosion resistance, but can chip if the film is cut.
Which finish is better for coastal and marine use?
Powder coating is often preferred at the coast for its thicker barrier and chloride resistance, especially with Qualicoat Class 2 or 3 and the Seaside qualification. Anodising also performs well at 20 microns or more, as set by Qualanod for coastal exposure.
Can I get any colour with anodising?
No. Anodising gives metallic tones, the natural aluminium colour or a dyed bronze, black or gold, with the metal grain still visible. For a specific RAL colour or a textured or matt finish, powder coating is the choice, offering the full RAL palette.
How thick is each finish?
Architectural anodising is about 15 to 25 microns to EN 12373, with Qualanod setting a 15 micron minimum and 20 microns for coastal use. Powder coating is about 60 to 120 microns to EN 12206, a much thicker film.
Does anodising chip like paint?
No. The anodised layer is grown from the metal’s own oxide, so it is integral and cannot chip, flake or peel. A powder coat is a film on the surface and can chip if it is struck or cut through.
What standards apply to these finishes?
Architectural anodising follows EN 12373 with the Qualanod quality label, and architectural powder coating follows EN 12206 with the Qualicoat quality label and its durability classes.
How do I clean anodised or powder-coated aluminium?
Wash with water and a mild, pH-neutral detergent, rinse and dry, and avoid abrasive pads and aggressive solvents. In coastal or industrial areas, clean more often to remove chloride and grime. No repainting is needed.
Does ULAMEX supply finished aluminium?
ULAMEX supplies aluminium profiles, sheet and fencing in mill finish and powder coated to order, and can advise on the finish for your colour, durability and environment, including when anodising is the better route.