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Thread: black stain under chuck - yuck

  1. #1
    Join Date
    Oct 2002
    Location
    Kirkland, Washington
    Posts
    2,173

    Default black stain under chuck - yuck

    I picked up a Rutland indexing spacer. Had a 3 jaw chuck mounted and all six plates. Decent quality mill accessory made in Taiwan. I took off the chuck and under it was a black stain.

    How can I get rid of this stain?

    Normally I'd post pics but I'm overseas so can't.

    metalmagpie

  2. #2
    Join Date
    Jan 2003
    Location
    Atascosa County, Texas
    Posts
    8,161

    Default

    If it's used, the stain is probably from cutting oil. Many use a chlorine enhanced paraffin that will rust or blacken cast iron and steel. I was using a 3M pad to buff off the spots I was getting before changing cutting fluid. If it's really bad, you might try buffing with a little phosphoric acid on the pad. Be sure to remove any oil first or the acid won't work.

    If the staining is merely dried packing/storage grease, try a midpoint solvent like naphtha. Mineral spirits may be too weak. Acetone or lacquer thinner is stronger but don't get it on any printed or painted labels or markings.

  3. #3
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    2,445

    Default

    Soluble cutting oil can leave that type of stain, it is merely cosmetic.

  4. #4
    Join Date
    Nov 2007
    Location
    Woodinville, WA
    Posts
    9,615

    Default

    The "stain" is probably a black iron oxide or iron/sulfur compound from the oils... corrosion. I have some starting on my Kurt vises. If you want to get it off you need to polish, grind or whatever. Are you sure you want to remove it??
    Last edited by lakeside53; 08-18-2019 at 11:10 AM.

  5. #5
    Join Date
    Jan 2003
    Location
    On the Oil Coast,USA
    Posts
    19,595

    Default

    Clean,re-assemble,don't worry about it.
    I just need one more tool,just one!

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