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Thread: Green smoke when soldering with sterling silver

  1. #1
    Join Date
    May 2014
    Location
    Denmark
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    Default Green smoke when soldering with sterling silver

    Hi everyone.

    I'm new in here and still learning how to solder. I solder in sterling silver, but have some problems I would like some help with. I just want to let you know that I'm from Denmark. If there is something I'm writing that doesn't make sense, please let me know and i'll explain it in a different way

    First of all, I started out soldering with plated silver, which I found out was a bad idea (the jewelry got a nasty black/brown colour.. we all know why) but the part where I soldered it together was looking good.
    So I brought sterling silver and start soldering.

    The first problem I got was that the torch set the silver alight which makes a green smoke and a nasty smell.
    The second problem I have is the place where I solder doesn't look very nice. I have to do a lot of polishing which doesn't even help that much - it still looks very homemade - maybe too homemade for my state. When I used plated silver the place looked very nice. I have tried to experiment with the different settings on my torch but I still can't make it look good.

    I would like to know what causes these problems and how to solve them. Any suggestions and tips more than are welcome!

    Kind regards
    Bine
    Last edited by Bine; 12-05-2014 at 10:59 AM.

  2. #2
    Join Date
    Aug 2010
    Location
    Surrey, England
    Posts
    1,868

    Default

    Welcome to the forum Bine,
    If your silver is burning then it is probably covered with a coating of plastic. Here in the UK some suppliers send us sterling silver covered this way to stop it tarnishing while in stock. When soldering, it is important to clean all surfaces manually before commencing. You can use abrasive papers or steel scraping tools. Solder joints and the solders all need to be cleaned this way, I use a three square steel scraper for this purpose. All solder joint surfaces need to be fluxed and all solder pieces also. I use borax as my flux. Here in the UK we have a Borax cone and borax dish and just add a little water before mixing the borax into a milky substance which is the added to the solder areas by means of a small paint brush. I cut small solder pieces and dip them in the borax before adding them to the solder joint.
    Sorry if this is too much info!
    James

  3. #3
    Join Date
    May 2014
    Location
    Denmark
    Posts
    8

    Default

    Quote Originally Posted by Goldsmith View Post
    Welcome to the forum Bine,
    If your silver is burning then it is probably covered with a coating of plastic. Here in the UK some suppliers send us sterling silver covered this way to stop it tarnishing while in stock. When soldering, it is important to clean all surfaces manually before commencing. You can use abrasive papers or steel scraping tools. Solder joints and the solders all need to be cleaned this way, I use a three square steel scraper for this purpose. All solder joint surfaces need to be fluxed and all solder pieces also. I use borax as my flux. Here in the UK we have a Borax cone and borax dish and just add a little water before mixing the borax into a milky substance which is the added to the solder areas by means of a small paint brush. I cut small solder pieces and dip them in the borax before adding them to the solder joint.
    Sorry if this is too much info!
    James
    Thank you for your answer.
    I use sulphuric acid 14% before I solder to clean the silver but it doesn't seem to work. I also got flux for solder pieces and silverpaste with flux in it. That's why I don't understand why it seems like there is a "coat" of something on the silver.

  4. #4
    Join Date
    Feb 2011
    Location
    Scotland
    Posts
    2,404

    Default

    Hello Bine
    I think James is correct and there is a plastic cover on your silver and you must remove this first, you should be able to peel it from the silver quite easily and then rub the area to be soldered with an abrasive paper. There is no need to use sulphuric acid especially if you have not removed the plastic covering!
    Whichever form of solder should then work, either small pieces with the flux you have chosen or silver solder paste. Clean silver sheet should never go on fire

  5. #5
    Join Date
    Jul 2009
    Location
    cotswolds
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    Default

    Solder paste contains organic binders which burn away during use - this can give a green flame. It's important to heat the metal, not the solder, however, as if you use the flame directly on the paste it will burn and become useless.

  6. #6
    Join Date
    May 2014
    Location
    Denmark
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    Default

    Quote Originally Posted by CJ57 View Post
    Hello Bine
    I think James is correct and there is a plastic cover on your silver and you must remove this first, you should be able to peel it from the silver quite easily and then rub the area to be soldered with an abrasive paper. There is no need to use sulphuric acid especially if you have not removed the plastic covering!
    Whichever form of solder should then work, either small pieces with the flux you have chosen or silver solder paste. Clean silver sheet should never go on fire
    Thank you! I will try abrasive paper and see if if works.

  7. #7
    Join Date
    May 2014
    Location
    Denmark
    Posts
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    Default

    Quote Originally Posted by mizgeorge View Post
    Solder paste contains organic binders which burn away during use - this can give a green flame. It's important to heat the metal, not the solder, however, as if you use the flame directly on the paste it will burn and become useless.
    I think you are right because I only experience this when using solder paste. Thank you for helping me!

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