Just can't seem to get aluminum siding clean! What works?

September 12, 2019 1:37 PM

I have very dirty aluminum siding on a house in the Midwest. I've tried many things, none work. Ideas?

I've tried:

* Pressure washer
* Simple Green
* Branded siding wash mixed w/bleach
* Trisodium Phosphate (TSP)

The last three I applied by dipping a scrub brush in and manually scrubbing. Doing this with Simple Green yields some cleaning, but when I look at the house from afar, I can see that it's still not that clean.

Any ideas?

Can't afford to repaint.

posted by 4midori to Home & Garden (10 answers total)

Professional power wash can be stronger than what you can do with your wash. Also, is there a chance it's mold or mildew, rather than just dirt?
posted by mmf at 1:41 PM on September 12, 2019 [1 favorite]

I don't have the answer, but Jolie Kerr (she does several cleaning columns, podcasts and wrote a book) might have some ideas. I have found her advice quite helpful in the past for a variety of cleaning conundrums and she seems to be someone who genuinely loves cleaning challenges. According to her Twitter, her email address is [e-mail]. If you don't get any good ideas here, might be worth a shot.
posted by emsuro at 2:14 PM on September 12, 2019

Is the paint still intact? Power washing particularly the high powered professional ones will thin/go right through the paint down to the aluminum.
posted by TheAdamist at 2:15 PM on September 12, 2019

Response by poster: * Yes, there is likely mold and mildew along with dirt.
* Pressure washer is powerful enough to strip paint.

Thanks for Jolie Kerr info.
posted by 4midori at 2:42 PM on September 12, 2019

I'm surprised the bleach didn't have much effect. Try a solution of pickling vinegar and isopropyl alcohol. Just mix them 1:1, then add a couple drops of dish soap. Have a go with a scrub brush.

This is mostly trying different solvents -- alcohol and a mild acid, with a detergent to lift any oils.

(Even if it doesn't work, you can put it in a spray bottle diluted 1:1 again with tap water and use it for general household/glass cleaning.)
posted by seanmpuckett at 2:48 PM on September 12, 2019

Is there a chance that what you're seeing as dirtiness is really dullness caused by the paint not being smooth/shiny anymore?
posted by amtho at 3:35 PM on September 12, 2019 [3 favorites]

I haven't tried it on siding, but Spray and Forget worked wonders on the roof shingles at our house (also in the Midwest).
posted by DrGail at 4:19 PM on September 12, 2019

Upper Midwest, mildew and mold on side of house. Aluminum siding.

Low-pressure spray with mildew-cutting detergent in pressure sprayer. Wait six or seven minutes. Scrub with medium-soft-bristle brush. Another low pressure spray with detergent. Then higher-pressure spray.

It was exhausting, frankly. And in some areas simply had to accept that repainting was necessary.
posted by Caxton1476 at 6:12 PM on September 12, 2019

I have had luck with SOS pads on vinyl siding where pressure washing and Simple Green/bleach mixture failed. Try it on a small spot to make sure it will not damage the paint.
posted by Short End Of A Wishbone at 9:24 PM on September 12, 2019

Does the siding look sort of grayish and dingy from a distance? Because if it's old siding and you've already cleaned it, that may not be dirt, the original powder coating may just be wearing off so that you see the unlying gray metal color of the siding coming through. I had my aluminum siding pressure washed a couple of years ago, and it made very little difference for that reason- a lot of dirt came off, but what was left behind still just looked dull and a bit shabby. If this is the case, you may be able to see a less gray color in any areas that get less weathering (i.e, behind shutters and drainpipes).

Hopefully that's not what's going on at your place, because if it is, there really isn't a way to fix it without repainting.
posted by Dorothea Ladislaw at 9:57 PM on September 12, 2019 [1 favorite]