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Thread: Black finish on bronze?

  1. #1
    Join Date
    Jun 2018
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    4

    Default Black finish on bronze?

    Hi, I was wondering if any of you know how to get a nice, uniform black finish on bronze?

    I tried liver of sulfur, and while I managed to get black colour, it was very fragile and flaking of at any opportunity. Then I sort of depletion gilded the bronze, so I'd have copper at the surface, but LOS still wouldn't work. It was a freshly opened patina gel, by the way, so that's not where the problem is. Everything was clean, and I tried different solutions, thinking that maybe what I was using was too diluted, or too strong, but nothing would work . I asked this question on facebook, in two jewellery groups I'm in, but I really didn't get any useful tips (apart from suggestion to try depletion gilding the bronze).

    Is there any patina solution that would create durable, smooth black finish on bronze? This can't be anything you need to be vat registered to buy, because I'm not, and I also live in the middle of nowhere in Northern Ireland, so I can't just go to the physical store at cooksongold or anywhere else.

    While looking on google, I found someone mentioning they managed to get dark/black finish on bronze by putting it in lye solution for a few days, but didn't really provide much info about how they did it. Did anyone here ever did this or heard about this? Because at this point I'd be willing to try that, but if this works, I'd have to dunk the piece in vinegar or other acid after rinsing, to neutralise the lye, and I'm not sure this wouldn't wreck my finish. Not to mention I'm not even sure how durable the finish would be... if it works at all.

    In case you need to know what I'm trying to do: I have two armour rings, each one with simple engravings on it, and I want to get the rings all black, in and out, and then run the engraving bit through the engravings again, to expose bronze only there. So sort of opposite of what people usually do. It's so annoying, I'm rather proud of them, but can't get them finished :/

    Does anyone have any ideas?

  2. #2
    Join Date
    Mar 2016
    Posts
    116

    Default

    You could try Black Ruthenium plating, though my understanding is that in order to ruthenium plate copper and it's alloys, you first need to plate a barrier layer of nickel, followed by plating in 18ct gold, before finishing with the ruthenium plating. See here: https://www.goldn.co.uk/product/blac...ting-solution/

  3. #3
    Join Date
    Dec 2009
    Location
    Central London
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    7,367

    Default

    I think Platinol, or Noirit (both from Cookson), applied several times and diluted with cold water would give you a fair dark grey result. The flaking is related to the speed of the chemical reaction, so to avoid it you must proceed as slowly as possible.

    In fact you might first go back to the solution you have and drastically retard it.

    That said, all patinas and even plating will wear away quickly in areas of repeated contact, so you are really doing it the wrong way round. Most people would darken the engraving, possibly only with a black waterproof pen and leave the body in the original colour. Dennis.

  4. #4
    Join Date
    Jun 2018
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    Default

    I looked at both of those, and these are the ones I can't get I know it'll wear off where there's friction, but to be honest, the bronze colour really isn't that popular with my target audience. I also know usually the flaking is related to having your patina solution too strong, but with weaker solutions the bronze just wouldn't get anywhere near being black, stopping at a weird, ugly, purplish-brown, no matter how long it spent in the solution.

    I guess on this one I just might want the impossible...

    But thanks for answering!

  5. #5
    Join Date
    Jun 2018
    Posts
    4

    Default

    Quote Originally Posted by Paul Kay View Post
    You could try Black Ruthenium plating, though my understanding is that in order to ruthenium plate copper and it's alloys, you first need to plate a barrier layer of nickel, followed by plating in 18ct gold, before finishing with the ruthenium plating.
    To be honest, this sounds way too complicated for me

    But thank you for the answer, I might use it at some point later on

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