Removing Dark Patina from Cast Iron?
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  1. #1
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    Default Removing Dark Patina from Cast Iron?

    For no real reason, decided to try to make my backplate, dog plate and dogs a little prettier

    Degreaser doesn't do it (Purple Power), is there a way to remove it? Considered spinning the plates on the lathe and carefully using Scotch Brite; perhaps bead blasting (for the dogs)?

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    If you take a fresh cut across the surfaces you'll expose fresh material that will be shinier. Depending on the quality of the CI it may end up a bit "hairy" too. I just did this on a face plate and it ended up shiny and hairy, but flat enough for my purposes. Wax may help prolong the look. Bead/sand blasting will turn it dull gray in my experience. In the end it isn't worth the effort. If you want it shiny and silver for a long time buy a new plate to look at or paint it.

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    I think of them more like a cast iron fry pan. They get "seasoned" over the years and I just tune them up with a bit of oiled Scotchbrite every few years.

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    Quote Originally Posted by tobnpr View Post
    For no real reason, decided to try to make my backplate, dog plate and dogs a little prettier

    Degreaser doesn't do it (Purple Power), is there a way to remove it? Considered spinning the plates on the lathe and carefully using Scotch Brite; perhaps bead blasting (for the dogs)?
    .
    .
    i work with fixtures and parts weighing tons. nylon abrasive and a coarse bench stone removes rust after you wiped any oil or grease off. then i wipe with alcohol rag and stone with a fine stone. rust and oil coolant the stone will not go over smooth. you will feel something is there. keep working at cleaning, stoning and eventually it stones smoothly
    .
    nylon abrasive pad in a 2 or 3" right angle air grinder speeds things up on really rusty stuff.

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    ScotchBrite or other non-woven abrasive pads. Generally four choices for how aggressive you want the grit to be. Rub with oil, makes a big difference.

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    You might try Evapo-Rust or similar product. There are a few products out there including one made by WD-40. These work pretty well with rust or like kind discoloration and are pretty much non-toxic watery solutions that you just soak your parts in for a few hours or overnight and parts come out looking pretty clean.
    CWC(4)

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    +1 on Evaporust. It is very good at removing things other solvents won't touch, like hardened coolant, while not harming paint. One other thing I use a lot is automotive wheel cleaner. Get the type that says " All wheels" or safe for painted wheels. If that won't get it off then Evaporust will

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    I use wd40 and a fine grit sandpaper or emory cloth, like 320 to 600 grit. Spay down the work and sandpaper, it won't leave scratches this way. Just wipe it off with a rag when done. Comes up nice imo.

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    Am I the only one that likes the patina?

    It seems like bright, fresh iron rusts more easily.

    Also I think darkened iron looks better, like the machine is a workhorse with some experience.

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    Sometimes I use solvent and very fine steel wool, seems to brighten it up a little

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    I've read this thread from day to day, wondering...why? Why go to all that trouble when the "patina" or modest oxidation will just come back? It'll be a never-ending occupation unless you clear-coat the pieces after polishing them up.

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    Doberman,

    I think people do this because "bright metal and new paint improve function, performance and accuracy" on old iron.

    Vlad

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