Stained Stucco

dpack

Long time listener, first time caller... Final clean up on a job and we aretrying to remove some difficult stains on the stucco (clay dirt splased up after rainand general roofing residue from newly cut composite slate tile) Tried pressure washer and did almost nothing! Also tried some elbow grease with some with stucco/siding cleanser from Home Depot...still nothing. Any suggestions..... Thanks.

nadonailer

maybe a little muriatic acid, diluted of course....... kinda like acidwashing a swimming pool

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dpack

I have ran that idea by a few people and they all do not recommend acid. It attacks the lime in the stucco and does nothing about the stain. I heard from someone today about applying a thin coat of the same stucco over the stain. Very diluted and applied with a brush then trowel smooth and flat. Throwing it out there.... thanks

DecksEtc

dpack, you don't need to post questions in two different areas to get a response. In actual fact it tends to annoy many of the regular posters. Most people here check for "new posts" when they come into the site. Don't worry it will be seen.

Just a friendly word of advice for you.

copusbuilder

We have had Iron ore stains on stucco jobs. We have never found a way to remove them? These were houses where we painted the trim and the owners decided to have us paint the stucco.
Of course they were establised and the gardens and grass were in to prevent a re-occurance.

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AAPaint

If they are iron/rust stains on the stucco, there is NO getting rid of them. The only thing you can do is seal them with a primer. The rust spots you speak of are caused by iron in the sand that was used for the stucco, and they will continue to appear over the years. As for the other stains if it's just dirt try some tsp mixed with a little tide detergent.

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AA Quality Painting & Pressure Washing LLC
Jacksonville Painters
Jacksonville, FL.

dpack

Terry, Go take, I'll make note of it. Thanks to everyone for the good advice.
Got about 95% of the stains out...client happy (thats what we are all shooting for!)

mightpeak

I have found that in areas with high humidity, there is the possibility of bleed through from corroding metal lath. I found a solution to this problem with a product called Fiberlath. It is a fiberglass opxy coated self furring lath.

Michigan Exhaust

Oxalic Acid works for these stains. Just for reference

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AAPaint

I understand that...but acid isn't great for stucco, and the stains will return. The iron is in the sand used to make the stucco. The sand was poorly sifted and over time there is no other way to deal with it than to seal it with a primer or for other rust stains caused by water sprinklers etc you can use a clear masonry sealer to prevent their return (for un-painted stucco, masonry, brick, etc.).

You also have to look at it another way. If you are there to pressure wash and find stains of this nature, it's an up-sell to seal or paint depending on the stains. If you're there to paint, you should have noticed them when bidding the job and charged appropriately for priming them. Either way it's a money making opportunity in my eyes and you can solve a re-occuring problem for your customer.....win/win!

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-AAPaint

AA Quality Painting & Pressure Washing LLC
Jacksonville Painters
Jacksonville, FL.