Guides
Anodised vs Powder Coated vs Thermal Transfer Finishes
A finish decides how a window looks in year one and how it ages in year ten. Three families do most of the work on aluminium: anodised, powder coated and thermal transfer. Each is applied differently, wears differently and matches colour differently. This guide compares the three on durability, colour range, RAL matching and performance in hot or coastal air, then shows how to confirm a finish on samples before an order is placed.
What each finish is
Anodising grows an oxide layer into the aluminium itself. The metal passes through an electrolytic bath and the surface converts to a hard oxide skin, so the colour sits inside the metal rather than on top of it. Powder coating sprays an electrically charged powder onto the extrusion and bakes it into a continuous film. Thermal transfer adds a powder base coat, then sublimates a pattern into that film so the surface carries a woodgrain or stone look. All three are applied at the factory to finished sections, which is why a finish is chosen before profiles are cut.
How each one wears
Anodised surfaces resist abrasion and handle sunlight well, though the colour range is narrow and a deep scratch goes through the oxide instead of blending in. Powder coating holds a thick, even film across a wide colour range, and its weak point is impact at edges and corners, where a chip can lift. Thermal transfer wears at the pattern first: the base film stays intact while the printed grain fades under strong sun. On all three, the question is how the finish behaves where the building stands and how easily it can be touched up if damaged.
Colour range and RAL matching
Powder coating carries the widest colour choice, because almost any RAL tone can be mixed and cured as a film. Anodising runs a narrower palette of metallic tones such as natural, bronze and black, and the exact tone shifts with the alloy batch. Thermal transfer adds woodgrains that a plain film cannot reach. Adam Alux matches finishes to RAL on request, so a project can hold one colour across windows, doors, mullions and louvers. Confirm the RAL reference on a physical sample, because a screen colour is not a coating.
Hot zones and sea spray
Sun and salt test a finish in different ways. Strong ultraviolet light fades a printed pattern faster than a pigmented film and dulls an anodised surface over time. Salt in coastal air attacks exposed fixings and can creep into a chipped powder edge, so choose a finish for the exposure and then keep the sections washed. Threads, fixings and cut edges deserve the same attention as the face of the profile, because that is where most coastal damage begins. Where a site sits close to the water, plan a rinse routine early.
Keeping one finish across a project
A building usually carries more than one aluminium product. Window frames, entrance doors, curtain wall mullions and shading louvers can come from different extrusions, and they read as different colours if they carry different finishes. Keep one finish family across the package and order it in one batch where the schedule allows. Where a mixed package is unavoidable, sample each product before ordering, because a woodgrain on a louver is not the same surface as one on a window sash.
Confirming a finish before you order
Work the choice in a fixed order. Decide the exposure class of the site, then the colour, then the finish family that delivers both. Write the finish and the RAL reference into the specification so the factory quote returns against a fixed target. Ask for a physical sample of the actual finish on the actual profile, and view it in daylight rather than on a monitor. The finish reference sits on the same sheet as the rest of the order, so ask for the dimensional pack with the quotation and check the colour line against your RAL.
FAQ
Frequently asked
Which window finish lasts the longest?
It depends on the exposure. Anodising resists abrasion but runs a narrow colour range, powder coating holds a wide colour range with impact risk at edges, and thermal transfer wears at the pattern first. In strong sun, keeping the sections clean matters as much as the finish family.
Can an anodised window be matched to a RAL colour?
Only within the metallic tones that anodising can produce. Its palette runs to natural, bronze and black, and the tone shifts with the alloy batch. Where a project needs a specific RAL reference, powder coating is the finish that can be mixed to it, and Adam Alux confirms colour on request.
Does thermal transfer fade in strong sunlight?
The printed pattern is the part that fades first, while the powder base film stays intact. In a hot, high-ultraviolet location a woodgrain surface loses depth over the years, faster on faces that catch the most sun. A rinse and wash routine slows the change.
Can different aluminium products share one finish?
Yes, and they should. Window frames, entrance doors, curtain wall mullions and louvers can come from different extrusions, so a mixed package reads as different colours if the finishes differ. Keep one finish family and one RAL reference across the package, and sample each product before ordering.
How do I confirm a colour before ordering?
Ask for a physical sample of the finish on the profile you are buying, and view it in daylight rather than on a screen, because a monitor colour is not a coating. Confirm the RAL reference in writing and check how cut edges are treated, then place the order.
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Series, glazing and finish come back as one quotation, with the full dimensional pack on PDF and CAD on request.