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  1. #1
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    Question Need help !! about polishing soldered brass/copper jewelry.

    I am currently working on a small piece of brooch (brass/copper), I have spent quite a long time soldering the pieces together and it has a lot of colorful "burnt" marks... I am not sure what I can do to remove the "burnt" marks and what should I use to polish it.


    Thank you!

  2. #2
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    Some pics would be good.
    But brass and copper polish up very easily. Citric/acetic acid will remove most oxidation and some flux from the surface. Heating the acid to 80-100 C will improve the effect considerably. Fine steel wool and scotch brite pads do a good job to polish. You cant beat buffing with rag wheels and compound for the final lustre

    Cheers Phil

  3. #3
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    Thanks for the reply ! ( http://i.imgur.com/aYMaIjI.jpg )
    this link is a picture of the jewellery (a brooch) that I've made, I have soldered both copper and brass together to create this funny looking beetle.
    I have all kinds of sanding papers for jewellery making but I have no access to acid.. can soaking the jewellery in vinegar remove the "burnt" mark?

    Thanks again!!

  4. #4
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    Being a small item, I wouldn't be using a bench grinder for that job, lots of bits sticking out a wheel can grab and either bend or fling the brooch against the wall/floor/ceiling/your head. A dremel type tool with buffing wheels and rouge is the way to go and should polish that up nicely. If you like you can make your own buffing wheels using a hole punch and some cotton cloth, you will go through a few. Any of the rouges will do the job; although, I'd stay away from green until the final buff, Bunnings stock jewelers rouge. Neither brass nor copper will hold their polished appearance for long so after polishing you'll need to coat the brooch with something. Removing the scale can be done a number of ways, just be careful if using abrasives to be gentle and not score the brooch's surface, very difficult to polish out score marks on such a small item. No idea which acids to use, never use them.

  5. #5
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    Quote Originally Posted by jmorbid View Post
    Thanks for the reply ! ( http://i.imgur.com/aYMaIjI.jpg )
    this link is a picture of the jewellery (a brooch) that I've made, I have soldered both copper and brass together to create this funny looking beetle.
    I have all kinds of sanding papers for jewellery making but I have no access to acid.. can soaking the jewellery in vinegar remove the "burnt" mark?

    Thanks again!!
    Vinegar contains about 4% acetic acid. Coke probably has a higher percentage of citric (?) acid, but I am only guessing here. It is used to clean coins much to the disgust of real coin collectors.

    Dean

  6. #6
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    Citric acid is available from your supermarket from the spice and baking powder section. It may also be labeled as food acid. Tartaric acid from the same section of the supermarket may also work, and both citric and tartaric acids are good for cleaning the calcium carbonate deposits from kettles as well, just add a couple of table spoons of acid powder to a full kettle of water, bring to the boil, and leave for 1/2 hour or so and the job will normally be done. Just rinse well before using for your tea or coffee.

  7. #7
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    Don't lick your fingers if using tartaric acid . The taste is something else again.

    Dean

  8. #8
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    Would molasses work?

  9. #9
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    Quote Originally Posted by sacc51 View Post
    Would molasses work?
    What? Licking your fingers? Ask a cow.

    Sorry. Couldn't resist.

    Dean

  10. #10
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    Nov 2007
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    Melbourne
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    What kind of solder and flux did you use?
    Was there instructions on the flux for removal?
    Peter

    Peter McBride Goldsmith Jeweller

  11. #11
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    Nov 2007
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    Melbourne
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    Might be of some use to explain what is happening to the copper and brass, and how to avoid the problem.
    A critical lesson to learn in jewellery making is to look more than a few steps to ahead to the things that will cause problems. Especially those involved with polishing. A little prevention is a whole lot better than a try at a cure .
    I've done this for more than forty years, and I'd have a real challenge to get a decent polish onto the brooch you've made.
    My usual metals are gold, platinum & silver, but I occasionally work in non-precious metals.
    Here are some pics and some notes on some brass and copper I just ran through a quick trial. It shows how to save a hell of a lot of work.

    Cheers,
    Peter

    First I took a 10 x 20mm rectangle of copper, and square of 60/40 brass, heated up to just on melting temps, cooled in air.
    What happens to the pure copper is similar to what happens to the copper alloyed in the brass, it reacts with oxygen, and some of the zinc is burned off and the copper is left at the surface and oxidizes.


    Then I placed it in a pretty innocuous pickling solution, alum in hot water, in a saucepan for 10 min just under boiling.



    scrubbed both with one of those wire toothbrush things from bunnings...it needs to be physically removed. File, emery paper polish etc. A more aggressive acid pickle solution will eat more away, but some folk are worried about acids.
    Next to the two pieces is another piece of brass I cut from the same strip, polished up a bit.


    After a painted coating with a generous layer of Boracic acid powder suspended in metho painted on, I burned the metho off leaving a coat of powdery flux (only on one side). I heated it up to red hot, the "flux" went glassy and coated the brass, and the back was oxidized just like the earlier two pieces (copper & brass) above.



    the back....


    Into the hot alum again for 10 min. I rubbed the piece of brass with a mixture of Bi-Carb Soda and water with my finger and thumb. The coated surface is great, the un-coated side is stained red like before.

    Attached Images Attached Images

  12. #12
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    Quote Originally Posted by lightwood View Post
    Might be of some use to explain what is happening to the copper and brass, and how to avoid the problem.............
    Hello Peter,

    Thank you for the wonderfully documented response.

    Bob.

  13. #13
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    I second that anorak-bob! Peter thank you for running through this process, I work with a lot of brass and also struggle to get a good clean after soldering. I've not heard of mixing the borax with metho, will give this a go. My main issue is the difficulty with removing any excess solder, I find I have to remove a lot of metal in order to get rid of the shadowy silver solder marks.. And no I don't flood it with solder I'm talking about only a little excess. I guess this is one of the issues of silver solder on yellow metal? Are there other solders one could try?

  14. #14
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    Quote Originally Posted by beck-t View Post
    I second that anorak-bob! Peter thank you for running through this process, I work with a lot of brass and also struggle to get a good clean after soldering. I've not heard of mixing the borax with metho, will give this a go. My main issue is the difficulty with removing any excess solder, I find I have to remove a lot of metal in order to get rid of the shadowy silver solder marks.. And no I don't flood it with solder I'm talking about only a little excess. I guess this is one of the issues of silver solder on yellow metal? Are there other solders one could try?
    Hi Beck,
    What solder and flux are you using?
    A picture of a problem joint will help me suggest removal strategies. My bench is covered in tools to remove metal in many different applications.

    A little more info about the metho mix.
    Not borax in the metho, boracic / boric acid powder is what to use.
    There is another very helpful step in the process. That is, I buy the boracic acid powder and find the particle size is a fraction large, so use one of these cheap coffee grinders to belt it into a very fine dust.
    Then in a jam jar, three or four table spoons to about 1/4 - 1/3 cup of metho.
    The larger particles tend to group together, but the fine dust gives a far better coverage after the metho is burned off.

    Soldering without excess solder flowing where you don't want is an art.
    Just remember, if you put too little on, you can usually, STOP... pickle it again, and reflux and put a little more solder in.
    What does happen when the solder is held for too long molten, or the flux has been cooked is, it stops flowing and the temptation is very strong to feed more in. Resist that. Go back a step and clean the joint and use a little solder.
    Experience will give you more certainty about how much solder to use. I still try and think every time I solder, "I must use less solder than I reckon the joint needs"!!
    Remember also, heat will drag the solder towards the hottest place. It is a balancing act to get right. So watch carefully as you solder and avoid the overheating, and holding the solder for too long molten.

    Good luck,
    Peter

    Just noticed, its your first post!
    Welcome!

  15. #15
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    Jul 2016
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    Australia
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    Peter thank you so much for this fantastic response I need to rifle through my things to find an appropriate piece and then photograph. Will send a proper response tomorrow!

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