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easy way to darken stainless steel

Discussion in 'Maintenance, Tinkering & Embellishment' started by Vulcanite, Jan 4, 2011.

  1. Vulcanite


    Jan 16, 2009
    I have some SS knives and some gun parts that I would like to DIY darken. I don't need them to be dark black, I just want to darken them somewhat so they are not so shiny and reflective. Can you use brass black to darken up stainless a little bit.

    I'm more interesed in a non-dimensional finish, somehting that works room temp or that can be set up w/ a torch or regular oven.

    Birchwood casey makes a bluing solution also something called presto black but they both say they are for non-stainless ferrous metals.

    I thought I heard you could use brass black on stainess, even though it only talks about brass, bronze and copper.
  2. Bill DeShivs

    Bill DeShivs KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 6, 2000
  3. Many people/makers etch dark logos or designs into stainless, using etching solutions made for the purpose. Might be able to adapt that (in a diluted form, perhaps), for dipping/soaking/painting the blade in the solution? Just an idea.
  4. eccvets

    eccvets Banned BANNED

    Sep 8, 2008
    soot from a flame?
  5. Vulcanite


    Jan 16, 2009
    is that a joke? I've happened to get knives or other tools blackened in a fire but it pretty much wipes off.

    What if you are ttrying ot grind SS stock? How can you get marking fluid on there so you know where to make your grind lines etc?
  6. Jason B.

    Jason B. KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 13, 2007
    If you heat hardened steel you will destroy it.

    A coating or rough sanded finish is the only ways I know of for stainless steels. Gun blue and other like products will not work.
  7. s_f


    Nov 17, 2009
    E.g. H2SO4, which you can find in car batteries (and therefore at many hardware stores).
    You should get a more or less dark grey afterwards and you'll have to experiment a little bit with the percentage of the acid and the time you leave your object in there.

  8. kelbro


    Mar 13, 2008
  9. ptradeco

    ptradeco Gold Member Gold Member

    May 26, 2010
    If all you want to do is knock the shine/polish off sand/bead blast it. Most machine shops have a cabinet and cost should be minimal. It does darken it a bit also.
  10. Vulcanite


    Jan 16, 2009
    sulfuric acid. You can buy bottles of it packaged as drain cleaner at the hardware store. How else can it be packaged? Can you by it in poweder form to make your mix.
  11. Vulcanite


    Jan 16, 2009
    will sulfuric acid eat up you edge?
  12. s_f


    Nov 17, 2009
    Pure sulfuric acid would be a liquid - but I dont know how to get it in the US.
    I would try using the stuff from a car garage or a hardware store which is supposed to be used for battery acid.* Concentrated acid may not work (i'm not sure anymore) but.. anything between 30 and 70% should do the trick.
    Of course: Be careful. Put the acid into some water - not the other way around. And dilute it when you're dumping it.

    IIRC most drain cleaners are made of chemical bases - not acids - and I'm not sure if they work for forcing a patina.

    It should work just as forcing a patina on carbon steels using weaker acids - so the very edge of knives will get weaker, too, but if you check the blade from time to time the patina layer shouldn't get too thick.
    But yes, it probably wont shave as good as before and you may need to resharpen/at least strop a little bit.

    Good luck! And again: be careful... can be dangerous stuff and it's easy to underestimate it... ((safety) glasses?)


    *: the liquid in car batteries is supposed to be diluted sulfuric acid - so about 10-20%. Since it's possible to dilute it with destilled water I assume they'll sell the acid at a higher percentage (33% ?)
    I dont know what I'd do if that doesn't work - probably trying to get stronger stuff (but still H2SO4) and leaving the objects in there for a longer time.
    Last edited: Jan 5, 2011
  13. nc527


    Mar 22, 2009
    I have a sandblasted 154cm blade, and after you oil it, it is rather dark grey. Could try that.

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