[Jewelry making - Article 00420] - Re: [Orchid] [Beginners' Corner] Making wire stronger

[Trevor F]

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>     As far as hardening Argentium, what's actually happening is that
>     the Argentium portion of the wire needs to be encouraged to rise to
>     the surface. This is done by gentle heating - a low temp kitchen
>     oven is more than adequate. This is done before the wire is ever
>     cut and used. No need to fear for stone that you may L> use with it.
>     It also tumbles well. 

    At the risk of revealing just how far behind I am in my Orchid
    reading I'd like to comment a little on the above. 

    I freely admit that wire-wrapping is not my thing so there may be
    subtleties in this conversation that I'm missing but... 

    What makes Argentium harder when you bake it is that you're
    rearranging the _internal_ crystal structure of the germanium in the
    alloy. In my experience a gentle bake is usually not sufficient to
    accomplish this. 

    For instance I see a noticeable difference in hardness between a
    piece of Argentium that has been baked at 500 F (260 C) for 40
    minutes VS a piece that is baked at 250 F (120 C) for 120 mins, for
    example. 

    I respectfully submit that the author of the above may be confusing
    the heat treatment of Argentium for tarnish resistance reasons VS
    precipitation hardening reasons. The two process work rather
    differently: 

    - for tarnish resistance any heating is good but (in my experience)
    more is better. What you are doing is encouraging the germanium in
    the alloy to migrate to the surface whereupon if spontaneously forms
    germanium oxide and that oxide gives you the alloy's tarnish
    resistant properties. Any heat, even room temperature, will do that
    assuming you're willing to wait long enough. 

    - for precipitation hardening purposes the "official" temperature of
    500 F produces far better results than say 250 F, for example. As
    mentioned above what you're doing here is heating the alloy so that
    the crystal structure of the germanium within the silver changes.
    This procedure is typically far more temperature specific, as is the
    case with precip hardening in other alloys. 

    There's more on both these subjects on my "Argentium" blog if you're
    so inclined. 

Cheers,
Trevor F.
in The City of Light
Visit TouchMetal.com at http://www.touchmetal.com

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