Mold on metal siding

I have a business wanting me to hit the mold on the side of their building. Never have done this . It’s raining all week here so I have time to figure this out . I still downstream with a 5 gal bucket. Metal siding is painted so I don’t think the SH will effect it? Thoughts???

Sorry I don’t have anything useful to say, except…dang.

@Mike11, nothing helpful to say, but man I hope you get the answer you need because that’ll make for some AWESOME before and after photos!

florida condo put out some infor on spraying metal, search for that if I don’t find it first and link it.

here it is

it is the post after racer’s, don’t know why it posted his reply

Is that whiskey mold?

Could be it’s a bar lol

Lol. Is there any whiskey plants or buildings in the area? A ton of buildings/houses in that area would likely be covered in the same type of mold.

That’s funny, but on a serious note I just talk to my buddy that owns washmartcom he told me the best way to do it is just regular downstream Mix And too Do it when the metal is not hot if it’s sunny outside make sure to soak it down And cool it off real good before you apply your mix. Best days to do it are overcast which works out perfect for me this week! Don’t let it dwell over 10 minutes

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Yeah DSing should work. Rinse rinse rinse like you’ve never rinsed before is what I’d do. Should turn out nice.

Great before and after. Do same as you would a steel roof, keep it wet and rinse as if it’s on fire.

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House wash add a little extra surfactant

Lye, Bleach, stp etc can and will hurt the metal, even though its painted the sides and fasteners used will rust and start poping quick… or slow. You can’t really use a bleach neutralizer like soidum theosulfate as it degrades metal, or even all the acids like ph down aka sodium metabisulfite will also hurt metal.

Id get a nanomicelles cleaner like g clean 1224 or WD-40 300363, it will blow your mind.

Then get a gallon of OdoBan Disenfectant for a post coat, its a quaternary ammonia. You could even add it to the cleaning pre treat and probably be good just make sure it sits for about 10 min before rinsing.

Probably needs a good gloss coat of paint afterwords.

Im sure i triggered some wanna be cowboys by not recommending bleach only but there ya go.

Good stuff :+1:

Have you tried this process before? Do you run a pressure washing company?


Yes I do but I’ve never done metal only been in business for 8 months. Been doing alot of house washes and flat work

I was replying to @onebluesummer


Just had something similar to do today, old painted aluminum sidding with lots of mold spots and yellow pollen or lychen???. The way i over came it was by downstreaming the siding twice. The fist time i waited 30 mins and the second time another 30 mins and it was alot easier to remove. If it doesnt come out after downstreaming twice, it will be soft enough you can use a green tip/jrod with a bigger orifice (to lower pressure) and it should come out like butter. Or 12 volt some 2-3% and it should melt away.

:+1: Sounds good cant do the job till next month. I’ll post after pics when I’m done.

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Looking forward to the after pics :+1:t2:

Any update?