Cleaning Aluminum Siding and Fixing Chalky Oxidation
Aluminum siding, common on older Lower Mainland homes, ages in a particular way: alongside the usual algae and grime, its painted surface oxidizes into a chalky, dull film that rubs off as a powder on your hand. Cleaning it is worthwhile and straightforward, but it helps to understand what oxidation is and what a clean can realistically achieve.
What chalky oxidation is
The finish on aluminum siding is paint, and over years of sun and weather that paint breaks down at the surface into a fine, chalky powder, oxidation. You can see it as a dull, faded look and feel it as a chalk that comes off on your hand or a cloth. On top of that, the siding grows the same algae and collects the same grime as any other in our climate.
So an old aluminum wall has two things going on: surface dirt and algae that clean off, and oxidized paint that is a breakdown of the finish itself.
How it is cleaned
Aluminum siding is soft washed: a suitable detergent breaks down the algae, grime and loose chalk, and it is rinsed at low pressure. High pressure is avoided, since it can dent aluminum and force water behind the panels. A gentle wash removes the dirt, the algae and much of the loose oxidized chalk, leaving the wall much cleaner and more even.
The result is a big improvement, the wall looks refreshed and the chalk and green are gone, though the underlying colour is limited by how far the original paint has faded.
What cleaning can and cannot fix
Cleaning removes the dirt, algae and loose chalk and restores an even, refreshed surface. What it cannot do is undo the fading of the paint itself, if the finish has oxidized heavily, the colour is permanently duller than when new. In that case, cleaning is the right first step, and repainting is the option if you want the original depth of colour back.
For most homes, a good clean is enough to make aluminum siding look cared-for again. An honest assessment sets expectations on how much of the dullness is removable dirt versus faded paint. Photos are enough for a quote.