From process to approval
What is the difference between anodized and powder-coated shower profiles?
An anodized profile carries an oxide layer made from its own surface; a powder-coated profile carries a cured coating laid on top. The Aluminum Anodizers Council (AAC) says in its FAQ that the aluminum oxide is grown from the aluminum by passing current through an acid bath in which the metal is immersed.
PCI describes powder coatings as polymer resin systems combined with curatives, pigments and other additives.
Hydro adds that anodizing is also used as a pre-treatment for powder coating.
| Term | What it means |
|---|---|
| Anodizing | AAC: aluminum oxide grown from the aluminum in an acid bath with current. |
| Powder coating | Hydro: dry powder applied electrostatically, then cured. |
| Class I, Class II | AAC: anodic coating classes with different minimum thickness. |
| Range sample | AAC: samples showing the color variation to expect. |
How is each finish made?
Steps 1 to 3 follow the AAC FAQ; steps 4 to 6 follow PCI, which describes electrostatic spray as the method typically used on metal.
- Anodizing: the aluminum is immersed in an acid electrolyte bath.
- Current is passed and an aluminum oxide coating grows from the metal.
- Color, where wanted, is added, for example by dye or by a metal salt deposited in the pores.
- Powder coating: a spray gun gives dry powder particles an electrostatic charge.
- The charged powder is attracted to the grounded part.
- The part enters a curing oven, where heat makes the coating react.
Before powder is applied, AkzoNobel’s Interpon D2525 Matt data sheet asks for a chromate conversion coating, a suitable chrome-free pre-treatment or suitable pre-anodising on aluminium.
Does the color tell you which process was used?
Not reliably. The sources below show black on the anodizing side and a near-unlimited color range, including a matte finish, on the powder side.
| Source | Finish | What the source says |
|---|---|---|
| MERLYN 8mm Squared Wetroom Black | Black wetroom screen | Anodised aluminium, matte black. |
| AAC FAQ | Black anodizing | Several organic dyes can give black. |
| Linetec anodize page | Anodize it offers | Clear, silver, champagne, bronze and black. |
| PCI | Powder coatings | An almost limitless range of colors and textures. |
| AkzoNobel Interpon D2525 Matt | Polyester powder | Smooth matt; gloss 20 to 30 GU at 60°. |
A dark matte color does not by itself identify the process. Ask the supplier to name the treatment in writing, with color and gloss as separate entries.
Which published documents cover each finish?
Anodic coatings and organic coatings on aluminum have separate specifications. The table gives each publisher’s public description, not the document text.
| Document | Published description |
|---|---|
| AAMA 611-26 | Architectural quality aluminum oxide coatings on aluminum extrusions and panels. |
| ISO 7599:2018 | A method for specifying decorative and protective anodic oxidation coatings on aluminium. |
| AAMA 2603-26 | Pigmented organic coatings on aluminum extrusions and panels. |
| AAMA 2604 and 2605 | Per FGIA’s December 2022 article on the 2022 editions, the more stringent tiers of the same series. |
| AAMA 609 & 610 | Cleaning and maintenance of anodized or painted architectural aluminum; a 2025 edition is listed as active. |
FGIA’s descriptions of AAMA 611 and AAMA 609 & 610 refer to architectural products. Whether a shower profile is finished to any of these documents is for the supplier to state and show.
What do class and thickness figures mean?
A class or thickness figure belongs to the document or maker that states it. Three examples:
Anodic Class I and II
AAC’s FAQ gives Class I a minimum coating thickness of 0.7 mil (18 microns), for exterior applications with periodic maintenance, and Class II 0.4 mil (10 microns), for interiors or exteriors cleaned on a regular schedule.
Powder film thickness
Hydro says powder thickness can be chosen from approximately 20 µm to a maximum of 200 µm. AkzoNobel’s data sheet gives Interpon D2525 Matt a minimum of 60 micrometres.
Organic coating tiers
In a December 2022 article on the 2022 editions, FGIA called AAMA 2603, 2604 and 2605 a “good – better – best” trio of increasingly stringent performance criteria for coatings of increasing minimum thickness. AkzoNobel’s data sheet states that Interpon D2525 Matt meets Qualicoat Class 2 requirements and, after five years of Florida exposure, AAMA 2604 requirements.
- The class or code, with its document named
- The thickness, its unit and whether it is a minimum
- The gloss value and measuring angle
- The pretreatment under a powder coat
Is one finish more durable than the other?
No test-based ranking for showers appears in the sources used here; one shower maker ranks its own finish. Claims and limits by source:
Claims for anodizing
Hydro lists corrosion and wear resistance, surface hardness, durable colour and gloss, and a significantly reduced risk of filiform corrosion, chipping, flaking, peeling or chalking.
Claims for powder
Hydro lists a precise colour match and an extra layer of protection from corrosion, scratching and chipping. PCI says powder gives a more durable finish than liquid paints.
Limits stated
Linetec says mortar, cement and other alkaline materials will quickly corrode an anodize finish if allowed to dry on the metal, and lists difficult touch-up as a limitation. AkzoNobel’s cleaning note for architectural components says powder coatings exposed to the elements may over time show loss of gloss, chalking and slight colour change.
Color consistency
Linetec’s page on color variation calls differences in alloy constituents the major reason anodize color varies and recommends metal from one source and one lot.
MERLYN states that the anodised black finish on its 8mm Squared Wetroom Black is more durable than powder coating. That is a maker’s claim for its own product; ask which test supports any such claim.
How should each finish be cleaned?
Follow the care sheet of the product supplied. The named sources agree on mild cleaners, but Sterling rules out abrasive sponges on anodized aluminum while the AAC FAQ suggests one.
| Source | What it says |
|---|---|
| Sterling care page, shower doors | Mild detergent diluted in water. No abrasive sponges or cleaners on anodized aluminum; no ammonia, bleach, acids, waxes, alcohol or solvents on metal surfaces. |
| AAC FAQ, anodized aluminum | No harsh acidic or alkaline cleaners; one technique is an abrasive cleaning sponge with mild dish washing liquid, tried on a small test area first. |
| AkzoNobel cleaning note, Interpon powder coatings | Warm water with a non-abrasive, pH-neutral detergent; a soft cloth or sponge; no abrasive cleaner or polish. |
How should a buyer specify and approve a profile finish?
These steps are procurement guidance, not a finishing specification.
- Name the treatment. Anodized or powder coated, recorded apart from color and gloss.
- Name the reference. The class, code or coating product the supplier works to.
- Approve a finished profile length. A flat chip may not show how the visible faces of the real section look in the room’s light.
- Ask for range samples. Agree the lightest and darkest acceptable pieces.
- Tie sample to profile. Keep the sample reference with the profile reference.
- Control changes. If the alloy, surface preparation or finish specification changes, ask which approvals repeat.
Matching across the enclosure
Profiles, handles, hinges and other fittings can use different metals and finishes even when the colors look alike. Record which sample belongs to which component, and name the match you need with nearby fittings.
What should you send and ask before a quotation?
A complete request names the process as well as the color.
| Question | Why it matters |
|---|---|
| Are the profiles anodized or powder coated? | The color name does not say. |
| Which class, code or coating product? | Figures belong to a named document or maker. |
| What evidence supports a durability claim? | A maker’s claim is not a test result. |
| Which care sheet applies? | Named sources differ on abrasives. |
| Do handles and hinges share the finish? | Parts can use different metals and treatments. |
Include with your request
- Color and gloss wanted
- Fittings that must match the profiles
- Enclosure type and quantity
- Sample length and faces to be viewed
WNS Global confirms any offered profile finish, sample and commercial terms separately in writing. This guide does not state that WNS Global profiles are anodized or powder coated, or that they have any class, thickness, test result or listing named above.
