In time, the factory paint will fade, get thin and will oxidize and become powdery/chalky. This will be very pronounced on areas exposed to sunlight. Wipe your fingers across the old aluminum siding and you’ll see the white powder/chalk all over your fingers. When washing this siding take care to not use too much pressure. How much is too much? In my opinion, anything much more than what you get out of a garden hose will be too much. Here’s why: using heavy pressure such as a pressure washer at a close in distance (less than 24″ or so) will remove the oxidized paint very unevenly and create very unsightly “zebra striping”. Therefor we usually use a mildew/detergent cleaning solution with very low pressure rinsing of aluminum siding. This will kill and remove the mildew, pollution and surface dirt…and without the zebra striping. You will still have the chalking on the surface but it will look as good as it can be.
Most aluminum siding in our area is now 30 years old or more. It is old and tired. It’s rarely going to look great again, just good… and of course will never look like new…unless you paint it. Additionally, areas of the aluminum siding that are under protected soffits & eaves and the like are usually not subject to the gentle rinsing & cleaning of normal rainfall. Over time the surface dirt and pollution, not washed away, will fester on the surface and produce permanent light to heavy staining which will not usually be removed by cleaning. These permanent stains are sometimes faint, sometimes obvious. They can usually be reduced but not eliminated.
When repainting aluminum siding we do utilize high pressure washing to prepare the surface. In this case it’s necessary to remove as much of the oxidized paint (the chalk) as possible to yield a properly cleaned surface for the paint to adhere to.
I hope you found this helpful. Please call or contact us if you have any further questions or would like to schedule a free consultation, or schedule a cleaning of your aluminum or vinyl siding, roof shingles, house, deck, fence, driveway, walkway, etc.