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chemical stain on milling table

Discussion in 'GENERAL SHOP RELATED DISCUSSIONS' started by quickcut, Sep 14, 2017.

  1. quickcut

    quickcut South Africa H-M Supporter - Premium Content H-M Supporter-Premium

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    Good day all , we had a chemical leakage (about 3 l) in our shop. The vapour from this has discoloured the table on my bridgeport clone, .This stain comes off with tons of elbow grease and a cloth soaked in diesel . Would it be okay to use a scotch-brite pad (the ones for pots) to clean the table? Any advice welcomed as this discolouration does not look good.
    thanks
    charles
     
  2. whitmore

    whitmore United States Active Member Active Member

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    It depends on the chemical, of course: if some fumes may have condensed on the cold metal, it could benefit from a water
    rinse or sponge-wipe, followed by blowing dry and immediately wiping down with oily rag.
    If 'tons of elbow grease' is required, diesel is probably NOT dissolving a residue, and another solvent
    (water, alcohol, maybe acetone) might be worth testing with.
    Yes, of course a scotchbrite pad is useful (there are pads for metal finishing that are more
    abrasive, like <https://www.mcmaster.com/#nonwoven-abrasives/=19djfc4>), or steel wool.

    Some chemicals (nitric acid, ferric chloride, chlorine bleach, oxalates etc.) can cause
    accelerated rusting, it's important to remove 'em and apply a bit of oil or wax because
    a pit can form (and attract moisture and promote rusting). Abrasives remove protective
    oxide layer (black iron oxide) but it grows back in a few days, which inhibits brown rust.

    It'd be a good time to examine lubricants, too (if it discolored metal, did it harm grease?).
     
    brino likes this.
  3. Randall Marx

    Randall Marx United States H-M Supporter - Premium Content H-M Supporter-Premium

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    To go a little further down the road suggested by Whitmore, I suggest checking the ways and such for similar conditions and cleaning everything very well to avoid any permanent damage.
     
  4. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    If I may ask, what was the chemical?
     
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  5. Ken from ontario

    Ken from ontario Canada Active Member Active Member

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    This is the best way in my opinion to remove rust or stains from cast iron surfaces, I never tried it on any other type of metal but for cast iron, it works great:
     
  6. quickcut

    quickcut South Africa H-M Supporter - Premium Content H-M Supporter-Premium

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    Thank you for all the replies, The chemical , believe it or not , was actually some sort of rust remover. It was so old that I think it had degenerated into some sort of toxic waste , including eating through the plastic container it was in. The liquid was easy to clean with toluene (we use this in our glue plant) but the vapour kind of oxidized the other surfaces. I used evapo-rust ? to clean the surfaces and while it did remove the oxidation it left the surfaces dull . I just want to brighten them up again. Scotch-brite scouring pad does work but I was hesitant about damaging the precision surfaces. Fortunately the ways were covered in oil and so protected. I am going to look at all those old solvents, etc and remove them from my shop. Not really fond of creating work for my self for no reason.

    charles
     
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  7. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Evaporust does not leave surfaces dull or frosted. The chemical that caused the corrosion is probably contained an acid, which do etch metal. Acids do not belong anywhere in a metal shop.
     
  8. sanddan

    sanddan Active User H-M Supporter-Premium

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    I use gray scotchbrite pads to clean the mill table and some surfaces on the lathe (not the ways). I usually use WD40 as a lubricant too. Gray is up around 800 grit I think, it's commonly used to scuff automotive clear coat before recoating.
     
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  9. quickcut

    quickcut South Africa H-M Supporter - Premium Content H-M Supporter-Premium

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    Thanks sanddan, I will use this as well. Haz mat material removal have been and taken everything that looks remotely suspicious.
     

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