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Powder coating versus anodising for aluminium windows and doors
How each finish is made, what colours and textures each allows, how they behave in monsoon and sea air, and which certificates and thicknesses to ask for. Figures that depend on the finisher are flagged.
Powder coating gives the wider colour range. Anodising gives a metallic look that is part of the metal.
Powder coating applies a dry polymer powder electrostatically and cures it under heat into a continuous film on top of the aluminium. Anodising converts the surface of the aluminium itself into a hard oxide layer through an electrolytic process. One sits on the metal, the other is made from it.
Most aluminium windows and doors in India are powder coated, because the colour and texture range is wide and the process suits large production. Anodising is chosen for a metallic finish and for parts such as sliding rails and bottom rails. Neither is better in absolute terms. Quality of pre-treatment, thickness, certification and application matter more than the label.
Two different processes on the same alloy
In powder coating, the section is cleaned and chemically pre-treated, sprayed with a charged powder, then cured in an oven. Common powders cure at about 200 degrees Celsius object temperature for around ten minutes, and lower-temperature powders exist. Pre-treatment is a multi-stage process of degreasing, etching and conversion coating, and it is the stage that determines whether the film stays bonded in damp, salty air.
In anodising, the part is the anode in an acid electrolyte. The oxide layer grows into and out of the surface, is porous, and is sealed afterwards. Dyes can be absorbed into the pores for colour before sealing. Because the layer is formed from the metal, it does not peel. It can crack under thermal stress, and general sources note it will not peel the way a paint can.
What you can specify in each
Powder coating can be applied in a very wide range of colours, with matt, textured and metallic variants in AluK’s palette, and with dual colour so that the inside and outside faces differ. AluK’s Signature Palette, for example, offers eight tones in matt, texture and metallic variants, and AluK lists dual-colour options across most systems.
Anodised finishes are in natural silver, bronze, black, gold and similar tones, with a subtle metallic depth that paint does not copy. Dye-based anodising cannot give white and has more limited colour range. Some reds and blues are prone to fading in sunlight, while black and gold from inorganic colouring are more lightfast. Batch-to-batch variation also needs managing, so order all elevations from one lot.
Powder coating: wide palette, textures, dual colour, matt to gloss
Anodising: metallic tones, subtle depth, limited palette, no white by dye
Both: the finish is applied after fabrication of the sections, so colour matching across components needs planning
DURABILITY
Near the sea, the pre-treatment and the certificate decide the life
For powder coating, QUALICOAT is the best-known approval scheme. Powder makers publish a cross-reference in which Class 1 corresponds to AAMA 2603, Class 2 to AAMA 2604 and Class 3 to AAMA 2605, and a Seaside Class requires a deeper pre-treatment etch, 2 g/m2 metal removal against 1 g/m2 for the standard route. AluK states Qualicoat-certified technology for its Signature Palette and over 20 years of durability, which is a manufacturer claim and not a warranty. The class is not stated on the page we read, so ask for the class and the certificate for the exact colour.
For anodising, the Indian standard for anodic coatings on aluminium is IS 1868. Thickness grades differ, and we have not confirmed the grade designations, so ask the anodiser to state the grade and the thickness in microns on the quotation. In both cases, the figure you want in writing is the thickness and the test method, not the word marine-grade, which has no single definition.
Both clean with mild soap, and both have limits
AluK India says to wash with a damp cloth, warm water and household detergent a few times a year, and no repainting is needed. Powder suppliers publish more frequent coastal intervals, around every three to six months for a high-salt coast against twelve to eighteen months on a low-salt coast in one supplier’s bulletin. Our maintenance guide sets out the routine.
Repair is a finisher question, and the options differ between the two processes. Ask what the finisher or the partner can do for a scratched or damaged section, and who pays, before you choose. Do not paint over either finish, because paint does not bond reliably to a cured coating.
Matching the finish to the opening
Our working guide is below. It describes how we would approach a decision with you, using AluK’s own specifications where they exist, and flags that final choices depend on the finisher and the datasheet.
Choose powder coating where you want a specific colour, dual colour or texture, or where the elevation matches a painted wall. Consider anodising where you want a metallic look, for hardware-adjacent parts such as rails, or where the architect has asked for it. AluK Home lists an anodised bottom rail on lift and slide, SC40 rails in anodised aluminium or stainless steel, and anodised as an option on BSF70NI. For coastal homes, see windows for the Goa climate and coastal homes.
Colour or texture is the priority: powder coating
Metallic, metal-like finish: anodising
Dual colour inside and outside: listed across AluK systems, so confirm it in your chosen finish
Rails, thresholds and high-wear parts: ask AluK, as some are anodised
Sea-front or high-salt exposure: ask for the Seaside class or equivalent, with certificate
BEFORE YOU ORDER
Three documents worth asking for
The finish certificate
For powder, the QUALICOAT or AAMA class and the licence of the applicator for the colour you chose. For anodising, the grade and the standard. Approval is specific to the product, so ask for the exact colour.
Film thickness and pre-treatment
Ask for the minimum thickness in microns and the pre-treatment route. Figures depend on the finisher and the datasheet, so we do not state a number here. A coastal site should be told which route is used.
Written care and warranty terms
Ask what cleaning is required to keep warranty, how often near the sea, and what voids it. Keep the page with the quotation.
How we handle the finish choice with a customer
Note the exposure
Distance from the sea, rain side, sun exposure, and whether the building is in a polluted or dusty area.
Choose colour and texture
See sample sections at the showroom, in daylight, and compare with your wall colour.
Ask for certificates
We request the finish class and the certificate for your chosen colour from the AluK Home partner who fabricates the work.
Set a care routine
The written instructions are kept with your quotation and handover.
FAQ
Finish questions
Direct answers, with figures flagged where they depend on the finisher.
Neither has a single answer. Lifespan depends on thickness, pre-treatment, exposure and care. Ask for the certificate and thickness for the product you are quoted, and for the written warranty terms.
Salt attacks weak points, so pre-treatment and an intact film matter. A Seaside Class process specifies a deeper etch before coating, and regular rinsing keeps salt off the surface. Ask which pre-treatment route is used.
Inorganic colours such as black and gold are lightfast. Some dyed colours, notably reds and blues, can fade in strong sun. Confirm with the anodiser for the colour you want.
Wood-effect finishes exist from powder suppliers. We have not confirmed an AluK wood-effect range, so ask the showroom what palette is available for your system.
An approval scheme for coatings on architectural aluminium, with classes that cross-reference AAMA 2603, 2604 and 2605 in powder-maker literature. Which class a given colour holds must be confirmed on the certificate.
It can be, depending on colour, size and the finisher. We have no sourced price comparison for India, so compare written quotes for the same section and finish.
Start with distance to the sea and ask for the highest class available for your colour. Then plan rinsing. See coastal homes and request a quote with your location.
