I soaked some Rusty tools in vinegar overnight and now they're all blackened. Any ideas on how to fix that?

Thanks!

my neighbor is a master body and paint guy. I saw him soak oxidized ferrous metal in muriatic acid. Came out clean as a whistle.

Um, if you go over to the knife section you'll probably find out that people do that exact thing on purpose. There is a reaction with the vinegar that produces a black patina on steel. It actually has a mild corrosion inhibiting affect. I think it is actually an oxide coating that forms similar to gun blueing. (my metallurgy is rusty, so don't hold me to specifics)

Cutting acidic foods with a knife will produce the same thing over time. Look at any old carbon steel knife and you'll likely see the black patina.

If you place rusty metal in vinegar long enough, you'll get vinegaroon (black paste) which is often used as a grain enhancing stain for wood finishing.

Ken

To remove rust from steel tools use a solution of citric acid. Citric acid powder is available at food canning supply stores or from Amazon. AIR, 5 lbs. is around $13.00.


It also cleans cartridge brass.

Should be able to just scrub it off with an SOS pad, although 8+ hours in the vinegar might be a bit much to do that.

FWIW, when I strip cast iron pans, after a several day soak in lye water I soak them in 50/50 vinegar/water to neutralize the lye and prevent flash rusting. Usually, though, I only leave them in there for an hour or so and then scrub them clean with an SOS pad. Clean as a whistle.

In the restaurant biz, we’d “treat” our brand new shiny high-carbon knives with a coat of mustard. It produced a dark patina, but they NEVER rusted.

quote:

Originally posted by matai:
I soaked some Rusty tools in vinegar overnight and now they're all blackened. Any ideas on how to fix that?

Thanks!

Could probably rub off with a little Rem Oil, WD40, or mineral spirits on a rag. If that won't do it, I'd move on to steel wool.