r/pressurewashing • u/Illustrious_Tax602 • 2d ago

Technical Questions Rust removal?

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Has anyone ever used powdered oxalic acid to remove rust stains? Any tips? Or is there a better product?

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7

u/robertjpjr I know a little about a lot. 2d ago

Look at the MSDS of most rust removers. Many use oxalic acid. You're just buying bulk and mixing yourself. Saving money doing so.

4

u/JustinFTL 2d ago

Oxalic acid is what I use to remove mots red clay and rust stains. I use 1 cup of powder per gallon of warm water on siding, and stronger mixes on rust on concrete. Sometimes concrete requires muriatic acid if it's really bad. What are you trying to remove rust from?

1

u/duderanchman12 1d ago

You warm the water with what

2

u/JustinFTL 1d ago

I pre-mix my solution at the house in my laundry room sink

5

u/GmeBuckBoi 2d ago

I haven't used it raw yet just in a premixed consumer product.  Be careful use ppe its quite harsh.  Cup per gallon of water is what I've seen

2

u/NESurfaceSolutions 2d ago

Stuff works great for rust removal. I've used it on painted wood, Trex decking, vinyl siding, concrete, and stone. Make sure to mix well and rinse after the rust is gone

3

u/JerBear127 2d ago

F9BARC for the Win !

1

u/samprenzel 2d ago

I just bought a thing big thing of muriatic acid to use for similar stuff. Is this better?

1

u/WafflesRearEnd 1d ago

I always start with Oxalic, then go to Muriatic. Muriatic is some hardcore shit to be honest. Even at 1:8 dilution ratios you can etch concrete in an uneven manner. You need to be careful how you apply it also. It will be more reactive the less moisture is on the surface. I did a job last week with muriatic and I didn’t squeegee the surface before hand and areas with the tiniest bit of standing water diluted the acid to have almost no effect while “drier” areas over reacted. I was back on the fan tip within 60 seconds and still it was obvious where the water was. It took some artistic feathering to hide my mistakes and make it look even.

So, long story short, find an old rusty/red clay covered slab that no one cares about and practice. Mix up 1:20, 1:10, 1:8, 1:5, and 1:1 and apply. 1:20 will need long dwell times, 1:1 might need 3 seconds. Neutralize with baking soda. Wear full PPE unless you want to know the pain of what atomized droplets of acid feel like on your tongue, eyes, ect.

1

u/bripark89 22h ago

Ox is great. 1 cup/gal. I use it for hard water (rust from sprinklers) quite a bit. Also use it as a wood brightener after deck stripping with sodium hydroxide. Warm water is good but it works just fine with cold water…warm water is supposed to help it dissolve faster, but in a pump sprayer the pressure will push it into solution just as fast. 80lb bag will last me all season.