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Thread: Platinum Ring stretching problem

  1. #1
    Join Date
    Oct 2015
    Posts
    2

    Default Platinum Ring stretching problem

    Hello,
    I have a plain platinum wedding band that I need to stretch, because my ring-finger is bigger than it was 10 years ago.
    I have not tried doing this resizing procedure before.

    Prior to stretching the ring, I wanted to anneal the metal to improve its ductility.
    Here is what I did:
    1) I cleaned the ring in a warm pickling solution of acetic acid (distilled vinegar) and salt (rather than using 10% nitric acid, for environmental reasons)
    2) Then I heated the ring to a dull-red colour with a butane powered micro blow torch, then I let it cool naturally. (no quenching)

    I then tried using a Rathburn ring stretcher, which I expected would be able to stretch the ring, but it seems to have no effect.
    I measured the internal diameter before and after with a digital vernier and it was unchanged.

    The ring's inner diameter is 17.5mm
    The ring's band has a comfort-fit cross-section, 2.4mm thick and 4mm wide.
    It weighs 10g

    So, what if anything am I doing wrong, or do I just need a bigger hammer for such a strong ring?
    Thanks

  2. #2
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    7,600

    Default

    Dear Nicholas,

    Those ring stretchers are barbaric and unpredictable. When it does work, it will be in leaps and bounds. I wouldn't give it house room.

    What you need is an upright ring stretcher, where you use gentle leverage and watch the ring descend, measuring intermittently with a separate ring stick, or in your case your finger.

    A jeweller can do it for you, or you can join a class. Dennis
    Attached Thumbnails Attached Thumbnails r Upright Ring Stretcher.jpg  

  3. #3
    Join Date
    Oct 2015
    Posts
    2

    Default

    Dear Dennis,
    Your reply only obliquely answers my question.
    Am I to infer that I wasn't doing anything technically wrong in the process, and that merely a greater and more evenly applied force is required?

    Regards,
    Nicholas Lee

  4. #4
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    7,600

    Default

    My reticence has a purpose. I have often enlarged gold and silver rings buy stretching, but platinum is not in my field.

    As far as I have read it is capable of being annealed by heating to an orange colour and then quenching, but I would hate to have you damage your ring. Hence my rant about that primitive ring stretcher.

    I also understand that platinum is easily contaminated when heated, so it should be done on a fresh clean surface.

    Other members here have first hand experience of platinum, but I'm afraid they will be involved in the usual end of year rush. Dennis.
    Last edited by Dennis; 11-11-2015 at 10:52 PM.

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