Painting Aluminium Window Frames: What Actually Works

A lot of the apartment and unit stock through St Kilda, Elwood and Balaclava went up between the sixties and the eighties, and it came with aluminium windows. Decades on, those frames are usually structurally perfect and cosmetically tired. The anodising has gone chalky, the powder coat has faded unevenly, and a bronze or mill finish that looked current in 1978 now dates the whole building.

Replacing them is expensive and, in a strata building, slow. Painting them is the obvious alternative, and it works. It just fails badly when it is done as though aluminium were timber.

Why aluminium is different

Paint sticks to most surfaces partly by soaking into them. Aluminium offers nothing to soak into. It is dense, non-porous and often already carrying a factory finish specifically engineered to resist things bonding to it. Anodising in particular is a hard oxide layer designed to be inert.

So adhesion has to be created mechanically and chemically rather than relying on absorption. That is the whole job. Every peeling aluminium frame anyone has ever seen was a frame where that step was skipped.

The preparation that actually matters

First the frame is cleaned properly. Not wiped, cleaned. Aluminium in a coastal suburb carries salt deposits, atmospheric grime and, on older anodised frames, a chalky oxidised layer that comes off on your hand. Any coating applied over that chalk is bonded to loose powder, not to metal.

Then the surface is abraded. A light scuff with a fine abrasive across the whole face gives the primer a mechanical key. On badly oxidised frames this takes a while, and it is the step most often rushed.

Then it is degreased with a solvent wipe, because sanding leaves residue and any oil or silicone left on the surface will cause the primer to crawl.

Finally, an etch primer or a dedicated metal adhesion primer goes on. This is the non-negotiable part. A self-etching primer chemically bites into the aluminium and gives the topcoat something to hold. Standard acrylic undercoat over bare aluminium will look fine for a season and then come off in sheets.

Topcoats

Once a proper primer is down, a quality exterior acrylic works well and stays flexible through temperature swings. Frames facing the bay get the same coastal-grade consideration we apply to any exterior work here, because salt is the thing that shortens coating life in this part of Melbourne more than anything else.

Two thin coats beat one heavy coat, particularly on window frames where a thick film will build up in the corners, sit soft, and interfere with the sash or sliding panel.

The moving parts problem

This is where sliding windows and doors need care. Sliders run in channels with fine tolerances. Paint in the channel, or a heavy build on the meeting stile, and the window binds. Tracks and running surfaces get masked rather than coated, and rubber seals are masked too, because paint on a seal goes hard and stops it sealing.

Anything that can be removed is better removed. Handles, catches and beading come off, get painted or cleaned separately, and go back on afterwards. It takes longer and it looks dramatically better than cutting around hardware.

What about windows in a strata building?

If you are in an apartment through St Kilda or Elwood, window frames are very often common property even though they are in your unit. That means the decision is not yours alone. Painting your frames a different colour to the rest of the building will usually get raised at some point, and it is far easier to ask the owners corporation first than to undo it later. Building-wide frame repaints are a common part of a scheduled repaint cycle.

When painting is the wrong answer

Sometimes it is. If frames have significant corrosion pitting, if the thermal break has failed, or if the windows are single-glazed and you were already considering replacement for comfort or noise, paint is money spent on something you will remove. St Kilda has plenty of buildings on busy roads where acoustic performance matters more than appearance.

Similarly, if a powder coat is delaminating in large flakes rather than simply fading, the underlying surface needs proper attention first.

The short version

Aluminium can absolutely be repainted, and on tired sixties and seventies frames it is one of the highest-impact things you can do to a building. Clean it properly, scuff the whole surface, degrease it, use a genuine etch or adhesion primer, keep the coating out of the running channels, and use a coating that can handle salt air.

Skip the primer step and it will peel. There is no version of this where it does not.

Window frame work usually forms part of a wider Exterior House Repainting job, and in apartment buildings it is often handled with the Interior Painting work at the same visit. On period properties with original timber joinery rather than aluminium, our Heritage and Period-Home Repaints service is the relevant one.