Rust stains on stucco

Are there any concerns using oxalic acid to remove rust from stucco? Are there better products? My concerns are the color fastness of the stucco.


but oxalic works. Keep it wet.


Thanks for bringing up F9. I didn’t want to influence anyone’s answer.

Is there anything else in F9 other than oxalic that give it an advantage?

We are cleaning his fence as well so I’ll have tons of oxalic mixed will try that first since I have experience with that product.

I’m not totally sure honestly. I just know it works faster than oxalic.

This is a premium product (aka expensive). I used it for a city monument and a few cemetary headstones. Look into quaternary ammonium products/solutions for more info.

This is hardly ever a good choice for a home, but this is a good product to know about and have in your arsenal when/if needed.


Just be ready to rinse the ox acid as soon as the rust is gone or it will lighten the color on the wall noticeably and avoid letting it run down the wall

I would use F9. Just mix it 2-1 water to chem in a cheap spray bottle. Spray it on, wait a few minutes, spray it again. The rust will literally disappear. Keep it wet till the rust is gone and then rinse. Won’t take more than 10min

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Another post reminded me, but Barkeeper’s Friend foam works fine on small stuff. If there’s a lot get oxalic or F9, but on stuff like this I’d probably try the Barkeeper’s friend first.

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Use a sponge with the oxalic to keep it from running down the wall and streaking anything up. Then rinse the area with a good amount of water. Repeat it again if necessary.

I read that one today as well. I remember @racer complaining he’d have to have one more product in his truck.

I order some F9 and EBC but not hopeful it will be here by Sunday. Will try my goto oxalic since it has worked well for me.

Where do you order from? iI will need to get some also.

Power wash store sells F9.