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Electroless Cobalt or Copy Chrome?

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  • Electroless Cobalt or Copy Chrome?

    Hey folks,

    I am looking to buy a "chrome" type electroplating kit in the next week or so, after I've finished my research.

    I can't decide what is better for my application, and I am looking for your insight and experience if you don't mind.

    I am making some aluminum lettering to stick on the back of my truck on my little CNC mill. After polishing, degreasing, and zincating the parts, which would be my best bet? I am looking for a show quality shine that will last through a Canadian winter. Triple chrome has been ruled out due to environmental concerns, and I don't see it as being necessary.

    I understand that Cobalt is a harder "chrome" like finish, but wonder if this makes post plate buffing a PITA? If that is the case, I will go with Copy Chrome. What substances do you use to post polish in either case? I have a good 5A power supply for my anodizing setup. Based on the fact that I really only plan to use this on emblems for myself and friends, which kit suits me best?

    Thank you,

    Joel

  • #2
    Re: Electroless Cobalt or Copy Chrome?

    Joel

    For Canadian harsh winter conditions I would recomend genuine chrome as the best most durable finish, even though you have ruled this out.

    The cobalt and nickel cobalt will both work equally as well but will require regular cleaning and mild polishing to prevent the harsh road grime from tarnishing the finish. I havn't tried electroless cobalt yet, but am led to believe it would be the second choice with any nickel finish as third choice.

    It is all in the final polishing. The better the final polish, the more resistant the finish is to tarnishing.

    For example I have done some tap ware in copy chrome. It is as hard as nails but it does discolour and require a light polish regularly to keep it looking nice.

    Hope this helps

    Mark

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    • #3
      Re: Electroless Cobalt or Copy Chrome?

      I would do the electroless cobalt if triple chrome is not possible. I've seen some misconceptions about Cobalt versus Chrome. Cobalt is not harder than Chrome. To the contrary Chrome registers about 8.5 on the Mohs scale while Cobalt registers about 5 (higher = harder). Cobalt is slightly harder than Nickel (which registers a 4 on the Mohs scale). However, it is not the slight difference in hardness that makes Cobalt superior to Nickle for decorative applications, it is what happens as you form surface oxides. Nickel will form a thin surface oxide layer that is dull and somewhat yellow. The oxide layer is self protective so the plated item will be protected, but decoratively it will not be as pleasing due to the dull slightly yellow appearance. Cobalt on the other hand will remain shiny and clear.

      Cobalt is not so hard as to be difficult to polish, in fact it should polish much like nickel. As most are aware, in typical chrome plating in actuality most of the plating thickness is in fact nickel, which is doing the bulk of the protection of the base metal. A final, relatively thin chrome layer is plated on last. It's function is to protect the nickel layer from oxidation so that the finish remains clear and shiny. In this application, it's not the hardness of chrome that is needed so much as it's ability to protect the nickel from oxidizing and turning yellow. Now, in high speed tool applications the hardness is the major characteristic that is important, along with chrome's low coefficient of friction and resistance to galling.

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      • #4
        Re: Electroless Cobalt or Copy Chrome?

        Thank you both for your insights.

        I was hoping to add to my anodizing setup with some more electroplating kits, so I can continue to learn and do this sort of thing on my own. I really enjoy it.

        I am doing this from my garage, so triple chrome concerns me. I did get a quote from a local plater to have genuine chrome plated onto these emblems, and he wanted $10 per letter. I guess it may be worth it to have him do the real thing for me, and let him be concerned with the proper environmental and ventilation procedures. It just seemed that even at the small quantities I planned to make, buying a kit would be more worthwhile for many reasons.

        I have not completely decided what to do yet, but I will take your advice on the electroless cobalt if I do decide to undertake this myself, engineerscott.

        KCV6: what do you use for a "final polish?" Does Caswell sell this as well? Will the same polish work on electroless cobalt? Thank you

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        • #5
          Re: Electroless Cobalt or Copy Chrome?

          Joel,

          I usually use the white and blue Rouge bars with a felt or loose cotton wheel. As with all abrasive cutting polish even the finest ones you have to be carefull that you don't cut through edges and corners. If your parts are all small I'd recomend the white rouge and a dremel or equivalent tool with the cheaper small felt bullets and wheels.

          The white cuts nickel/cobalt away, the blue barely cuts at all.

          For ongoing maintenance polishing I just use a good quality car wax like Meguiars or Turtle wax.

          Cheers

          Mark

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