Key takeaways
- Anodizing is part of the metal; powder coating is a layer on top of it.
- Anodizing is thinner (5–25 µm) and harder; powder coating is thicker (60–120 µm) and more colorful.
- Anodizing keeps a metallic look; powder coating offers any RAL color, texture or wood-grain.
- Both last decades outdoors when the right class or grade is specified.
- Allow for finish thickness on tight fits — especially with powder coating.
Anodizing and powder coating are the two most common finishes for aluminum extrusions. Both protect the metal and both can last decades, but they work in completely different ways — and that difference decides which is right for your part.
How they work
Anodizing is electrochemical. The profile is made the anode in an acid bath, and an oxide layer grows from the aluminum itself. The layer is then optionally colored and sealed. Because it is part of the metal, it cannot peel or flake.
Powder coating is a paint process. After a chemical pretreatment, a dry powder is sprayed electrostatically onto the profile and cured in an oven into a continuous polymer film that sits on top of the metal.
Side-by-side comparison
| Anodizing | Powder coating | |
|---|---|---|
| Typical thickness | 5–25 µm (hard anodizing: 25 µm +) | 60–120 µm |
| Appearance | Metallic, translucent | Opaque, any look |
| Colors | Clear, black, bronze, champagne; dyed colors | Any RAL or matched color, metallics, wood-grain |
| Hardness and abrasion | Very hard, excellent abrasion resistance | Good; can chip under impact |
| UV stability | Excellent for clear and electrolytic colors | Excellent for super-durable polyesters |
| Hides surface marks | No — die lines can show through | Yes, largely |
| Effect on dimensions | Small (about half the layer grows outward) | Significant on tight fits |
| Electrical | Insulating layer | Insulating layer |
| Repair on site | Difficult | Touch-up paints available |
| Common standards | EN ISO 7599, AAMA 611, Qualanod | Qualicoat, AAMA 2603/2604/2605 |
Choose anodizing when
- You want a metallic look — silver, champagne, bronze or black.
- The part faces abrasion or handling — handrails, door handles, framing.
- Tight fits leave no room for a thick coating.
- You need a surface that cannot peel.
Choose powder coating when
- Color matters — brand colors, RAL schedules, textures or wood-grain.
- The alloy or surface would not anodize evenly, for example with visible die lines.
- You need to hide minor marks on visible faces.
- The project calls for a specific architectural coating grade.
What about e-coat?
Electrophoretic coating combines both ideas: a thin, smooth acrylic film applied over anodizing. It keeps the metallic look while adding protection against mortar, pollution and cleaning chemicals — popular for windows and doors.
Specifying either finish
Always state the class or grade (for example “anodized AA20, clear” or “powder coated, Qualicoat class 2, RAL 7016 matte”), identify visible faces, and mark masked areas such as threads and grounding points. Approve a reference sample before production.
Need advice for your project? Send your drawing and finish requirements.
Frequently asked questions
Which lasts longer outdoors, anodizing or powder coating?
Both can last decades. Anodizing's durability depends on its thickness class and sealing; powder coating's depends on the resin grade — super-durable polyesters hold color and gloss much longer in strong sunlight.
Can powder coating be applied over anodizing?
It is possible but uncommon, because adhesion on sealed anodic layers needs special preparation. Aluminum is normally given a chemical conversion pretreatment before powder coating instead.
Which finish is cheaper?
It depends on color, class, volume and part geometry. Clear anodizing and standard-color powder coating are often similar in cost; special colors, thick anodic classes and small batches cost more.