Sliding windows
Sashes slide horizontally on rollers, saving space on balconies, in apartments and in hotel rooms. Suits wide openings; multi-track and lift-and-slide versions available.
Window finishes
Powder Coated Aluminium Windows
Powder coated aluminium windows have frames finished with a baked-on layer of polyester or fluoropolymer powder, giving any RAL colour in matt, satin, gloss, textured, metallic or woodgrain effects. The finish lasts as long as its specification: the pretreatment, powder class and film thickness decide whether a frame still looks right after five years or after twenty-five. Metline supplies powder coated window profiles to Qualicoat and AAMA grades to window fabricators for residential, hotel and commercial projects worldwide.
- Profiles
- 6063-T5 / T6, 6060-T66
- Coating grades
- Qualicoat 1 – 3, AAMA 2603 – 2605
- Colours
- Any RAL, metallic, woodgrain
- Window types
- Sliding, casement, awning, fixed
What is a powder coated aluminium window?
Powder coating is a dry finishing process. Finely ground resin, pigment and additives are sprayed onto the aluminium profile through an electrostatic gun, so the charged particles wrap around the earthed metal and cling to it. The profile then passes through an oven, where the powder melts, flows into a continuous film and cross-links into a hard, durable coat. No solvents are used, overspray can be recovered, and a single coat typically builds 60 – 80 µm, far thicker than a liquid paint coat.
For windows, the profiles are normally coated as straight extrusions before they are cut, machined and assembled into frames and sashes. Coating the full length gives even colour along every face, while the cut ends are concealed inside corner joints and sealed. Thermal break profiles can be coated before or after the polyamide strips are rolled in; coating before assembly allows a different colour inside and outside, a popular option where the facade calls for anthracite but the interior suits white.
Powder coating is the most widely used finish for aluminium windows today because it combines a near-unlimited colour range with good durability and a low cost per square metre. Its main competitor is anodising, which suits projects that want a metallic appearance; the two are compared later on this page.
Powder coated window profile specification options
| Item | Options |
|---|---|
| Profile alloy | 6063-T5 or T6 (Americas, Asia, Middle East), 6060-T6 or T66 (Europe); 6061-T6 or 6005A-T6 for heavy commercial mullions |
| Profile system | Non-insulated, thermal break, slim-frame, heavy-duty commercial or custom sections |
| Wall thickness | Typically 1.2 – 2.0 mm for residential frames, 2.0 – 3.0 mm for large commercial windows and high wind loads |
| Window types | Profiles for sliding, casement, tilt and turn, awning, hopper, fixed and combination windows, plus matching doors |
| Coating | Polyester, super-durable polyester or fluoropolymer (PVDF / FEVE) powder |
| Specification | Qualicoat Class 1, 2 or 3; AAMA 2603, 2604 or 2605; EN 12206-1 |
| Gloss | Matt (about 0 – 30 GU), satin or semi-gloss (31 – 70 GU), gloss (71 – 100 GU) |
| Glazing pocket | Beads and gaskets to suit single, insulated, Low-E, toughened, laminated, acoustic or solar-control glass |
| Hardware | Handles, locks, hinges, friction stays, rollers and gaskets matched to opening type; preferred brands on request |
| Packing | Protective film, foam, edge guards, profiles labelled by window number, bundled or crated |
Coating grades: Qualicoat and AAMA explained
Two specification systems dominate architectural coatings on aluminium. Qualicoat, based in Switzerland, is used across Europe, the Middle East, India and much of Asia. The AAMA voluntary specifications, published by FGIA, are standard in North America. Both grade coatings by how much colour and gloss they retain after outdoor exposure in Florida, the benchmark test site for high UV and humidity.
| Grade | Outdoor exposure test | Main retention requirement | Typical use |
|---|---|---|---|
| AAMA 2603 | Optional 1 year, South Florida | Basic colour and chalk limits | Interior and low-exposure exterior parts |
| AAMA 2604 | 5 years, South Florida | Gloss retention at least 30 %, colour change ΔE no more than 5 | Residential and commercial windows |
| AAMA 2605 | 10 years, South Florida | Gloss retention at least 50 %, colour change ΔE no more than 5, plus severe humidity and salt-spray tests | High-rise, monumental and coastal projects |
| Qualicoat Class 1 | 1 year, Florida | Gloss retention at least 50 % | Standard architectural use |
| Qualicoat Class 2 | 3 years, Florida | Gloss retention at least 50 % with tighter colour limits | High-UV climates, dark and bright colours |
| Qualicoat Class 3 | 10 years, Florida | High gloss and colour retention, comparable to PVDF | Premium and long-life facades |
Summarised from published AAMA and Qualicoat requirements; consult the current edition of each specification for the full test list and limits.
As a working guide, Class 1 or AAMA 2604-level polyester powder suits most homes in temperate climates. Specify Class 2 or AAMA 2604 super-durable powder in strong sun, at altitude or for dark colours, and Class 3 or AAMA 2605 for high-rise buildings, prestige projects and coastal sites where repainting would be expensive or impossible.
How aluminium window profiles are powder coated
- PretreatmentProfiles are degreased, etched and given a conversion coating, today usually chrome-free (zirconium or titanium based). For coastal work, a deeper etch or anodic pre-treatment is used to reduce filiform corrosion.
- DryingThe profiles are rinsed in demineralised water and dried so no moisture is trapped under the coating.
- Electrostatic applicationAutomatic and manual guns apply powder evenly to visible faces, with attention to corners and recesses where the electric field is weaker.
- CuringIn the oven, the metal is held at the powder maker's cure schedule, typically around 180 – 200 °C for 10 – 15 minutes at metal temperature, so the film fully cross-links.
- Inspection and testingEach batch is checked for colour, gloss, film thickness, adhesion and appearance before profiles go on to fabrication.
The extrusion itself affects the result. Die lines, scratches, pick-up and inconsistent surface alloy chemistry show through a thin film, so window profiles use alloys with tightly controlled iron and silicon and are handled to protect visible faces. Undercured powder looks fine on day one but chalks and loses gloss early, which is why cure verification (for example a solvent rub test) is part of routine quality control.
Quality checks for powder coated window frames
| Test | Method | What it shows |
|---|---|---|
| Film thickness | Eddy-current gauge, ISO 2360 | Enough coating for protection; Qualicoat requires a minimum average of about 60 µm for Class 1 and 2 powders |
| Adhesion | Cross-cut test, ISO 2409 | Bond between coating and pretreated metal; should show no detachment |
| Gloss | 60° gloss meter, ISO 2813 | Matches the ordered gloss level within tolerance |
| Colour | Visual against approved panel and spectrophotometer (ΔE) | Colour match to RAL code or sample and batch-to-batch consistency |
| Cure | Solvent rub test | Full cross-linking of the film |
| Impact and bend | ISO 6272 impact, ISO 1519 mandrel bend | Flexibility; coating does not crack when profiles are handled or bent |
| Corrosion | Acetic acid salt spray (ISO 9227) and Machu test, on qualification panels | Resistance of pretreatment and coating to creep corrosion |
For project orders, approve a physical colour panel before production and keep a retained sample for reference. Coating all profiles for one facade in as few batches as possible, and from the same powder lot, keeps colour consistent across a building.
Window types our coated profiles suit
Casement windows
Side-hung sashes open fully for ventilation and seal tightly on gaskets. Good air, water and sound performance for homes, villas and offices.
Tilt and turn windows
Tilt inwards for secure ventilation, turn inwards for cleaning and full opening. Common in Europe and high-rise housing.
Awning and hopper windows
Top-hung or bottom-hung sashes for kitchens, bathrooms, schools and corridors, ventilating even in light rain.
Fixed windows
Non-opening frames for large views, stairwells and feature glazing; the slimmest sightlines and lowest cost per square metre.
Matching door profiles
Sliding, hinged, bifold and lift-and-slide door profiles in the same colour and system family, for a consistent facade.
Colours and finishes for powder coated windows
Any colour can be produced, but most projects choose from a small group of architectural favourites. The table lists common choices and what to consider for each.
| Colour | Example RAL | Character | Points to consider |
|---|---|---|---|
| Anthracite grey | RAL 7016 | Modern, the most specified window colour in Europe | Absorbs heat; choose a durable class in hot climates |
| Black | RAL 9005, textured black | Strong contrast, contemporary and industrial styles | Shows dust and fades fastest if a low-grade powder is used |
| Traffic or signal white | RAL 9016, 9003 | Clean, bright, suits light facades and interiors | Shows dirt; easy colour match for replacements |
| Grey aluminium and silver | RAL 9006, 9007 | Metallic look similar to anodising | Metallic powders need careful batch control and may need clear topcoat |
| Bronze and brown | RAL 8019, bronze metallics | Traditional or warm modern facades | Popular for heritage-style replacements |
| Woodgrain | Sublimation over base coat | Timber appearance on aluminium | Specify exterior-rated films and inks |
- Match the hardware: handles, hinges and visible screws should be ordered in the same or a deliberately contrasting colour.
- Consider heat: dark frames reach surface temperatures 20 – 30 °C higher than white ones in direct sun, which increases thermal movement; good systems allow for it.
- Texture hides wear: fine-textured powders conceal minor scratches and fingerprints better than smooth gloss finishes.
- Dual colour: on thermal break profiles, inside and outside colours can differ at little extra cost.
Powder coated vs anodised aluminium windows
| Aspect | Powder coated | Anodised |
|---|---|---|
| How it works | Organic film fused onto the surface | Oxide layer grown from the aluminium itself |
| Typical thickness | 60 – 120 µm | 15 – 25 µm for exterior (EN ISO 7599 / Qualanod) |
| Colour range | Unlimited, including textures and woodgrain | Silver, champagne, bronze, black and a few others |
| Appearance | Opaque, uniform colour | Metallic, shows the metal beneath |
| Abrasion resistance | Good | Excellent; very hard surface |
| UV resistance | Depends on powder class | Excellent for clear and electrolytically coloured films |
| Repair on site | Touch-up paint possible | Difficult to repair invisibly |
| Main risk | Filiform corrosion if pretreatment is poor | Colour variation between batches; staining from alkaline mortar |
Choose powder coating when the facade needs a specific colour, when doors, windows and cladding must match, or when budget favours it. Choose anodising when a metallic appearance and very hard surface are the priority. Some projects combine both: anodised trims and curtain wall caps with powder coated window frames.
Common powder coating defects and how to prevent them
| Defect | What you see | Usual cause | Prevention |
|---|---|---|---|
| Filiform corrosion | Thread-like worm tracks under the film, starting at cut edges or holes | Weak pretreatment combined with salt and humidity | Seaside-grade pretreatment, sealed machined edges, regular washing |
| Chalking and fading | Powdery surface, loss of colour and gloss | Low-durability powder in high UV, or undercure | Correct coating class for the climate; verified cure |
| Poor adhesion | Coating flakes or lifts in sheets | Contaminated or inadequately pretreated surface | Controlled pretreatment line, cross-cut testing on each batch |
| Orange peel and runs | Uneven, dimpled or thickened surface | Excess film build or poor gun settings | Thickness control within specified range |
| Colour mismatch | Visible shade differences between frames | Different powder lots or batches | Single powder lot per project and approved reference panel |
Most failures seen on site are not caused by the powder itself but by what happened before and after coating: inadequate cleaning and conversion coating, scratches during fabrication left unrepaired, or mortar, cement and acidic cleaners splashed onto frames during construction. Keep the protective film on until wet trades are finished, then remove it promptly, since film left for months in strong sun becomes difficult to peel and can leave adhesive residue.
Where powder coated aluminium windows are used
- Housing and apartments: white, grey or black casement and sliding windows, often with insulated glass and dual colours.
- Villas and premium homes: slim-frame and large fixed windows in anthracite, black or bronze, with matching sliding doors.
- Hotels and resorts: uniform colour across hundreds of rooms; coastal resorts need Class 2 or 3 coatings and marine pretreatment.
- Offices and commercial buildings: ribbon windows and punched openings matched to curtain wall and cladding colours.
- Schools and hospitals: durable textured finishes that hide wear, with restricted-opening hardware.
- Shopfronts: fixed and door frames coated to brand colours.
In coastal locations, the coating class matters less than the pretreatment and the detailing. Filiform corrosion starts at cut edges and drilled holes, so seal machined areas, specify a seaside-grade pretreatment and wash frames periodically to remove salt deposits.
What affects the price of powder coated aluminium windows?
Size and type
Larger windows need deeper profiles, thicker glass and stronger hardware; opening sashes cost more than fixed lights.
Profile system
Thermal break and slim-frame systems cost more than basic non-insulated sections.
Glass
Low-E, laminated, acoustic and triple glazing raise cost but also performance.
Coating grade
Super-durable powders and Class 3 / AAMA 2605 systems cost more than standard polyester.
Colour and effect
Standard white, black and grey are economical; special RALs, metallics and woodgrain add cost, especially in small quantities.
Hardware, quantity and packing
Hardware brand, number of locking points, order volume and export packing all affect the delivered price.
Information needed for a quotation
- Window scheduleTypes, opening directions, sizes and quantities, or drawings and elevations.
- FinishRAL code or colour sample, gloss level, texture, coating grade (Qualicoat class or AAMA number), single or dual colour.
- Glass and hardwareGlass build-up and performance targets; handle, lock and hinge preferences.
- Site conditionsCountry, coastal or inland, building height, and any air, water, wind, thermal or acoustic requirements.
- DeliveryPacking and labelling requirements, delivery batches and destination port; Metline confirms terms (EXW, FOB, CIF or DAP).
References and standards
- Qualicoat – Specifications for a quality label for coatings on aluminium for architectural applications
- AAMA 2603, 2604 and 2605 – Voluntary specifications for pigmented organic coatings on aluminium extrusions and panels (FGIA)
- EN 12206-1 – Paints and varnishes: coating of aluminium and aluminium alloys for architectural purposes, Part 1: powder coatings
- ISO 2360 – Non-conductive coatings on non-magnetic conductive base metals: measurement of coating thickness (eddy current)
- EN ISO 7599 – Anodizing of aluminium and its alloys: decorative and protective anodic oxidation coatings
Powder coated aluminium (aluminum) windows: FAQ
How long does powder coating on aluminium windows last?
A correctly pretreated and cured standard polyester coating typically keeps an acceptable appearance for 15 – 20 years in moderate climates; super-durable and Class 3 / AAMA 2605 systems last longer and are often backed by manufacturer warranties of 20 years or more. Coastal and high-UV sites shorten life unless the grade is chosen for them.
Are black powder coated windows suitable for hot climates?
Yes, if you specify a super-durable or fluoropolymer powder and a system designed for thermal movement. Black frames get much hotter than white in direct sun, so standard polyester can fade faster, and long frames expand more.
Which is better, powder coating or anodising?
Neither is better in all cases. Powder coating offers unlimited colours and textures and is easy to touch up. Anodising gives a hard, metallic surface that cannot peel. Choose by appearance, budget and exposure.
Can powder coated aluminium windows be recoated?
Yes. The surface must be cleaned, lightly abraded and checked for adhesion, then recoated with a compatible liquid coating on site or stripped and powder coated again in a workshop. Painting directly over a dirty or chalked surface fails quickly.
How should powder coated frames be cleaned?
Wash with clean water and a mild, pH-neutral detergent using a soft cloth or sponge, then rinse. Avoid abrasive pads and solvents. Twice a year is enough inland; near the sea, clean every three months to remove salt.
Can inside and outside be different colours?
Yes, on thermally broken profiles the inner and outer aluminium shells are coated separately before assembly, so any combination of colours is possible.
Can I get a quotation without complete drawings?
Yes. Building type, approximate window sizes and quantities, colour and site location are enough for a budget price; final pricing follows once drawings and a window schedule are available.
Need powder coated windows for a project?
Send your window schedule, colour, coating grade, glazing and destination to sales@metline.in for a profile proposal and delivered quotation.
