[Jewelry making - Article 01589] - Re: [Orchid] To quench or not to quench, that is the question

[jesse Brennan]

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    I haven't paid attention to this series this time, but you don't need
    to go to cherry red and if you do quench in water (never pickle)
    almost immediately a little slow handling won't hurt. Annealing is
    practically instantanious at this temperature and too long will cause
    rapid grain growth. 

    Each annealing step makes this worse. Large grain growth will ruin
    the metal for further working and may cause later cracking. You can
    only recover large grained metal by melting. I batch anneal in a
    furnace and don't get very hot (400- 450 C) but hold it longer--
    grain growth is not a problem at this temperature. Commercial
    annealing will be done in continuos belt furnaces with a protective
    atmosphere. the temperature is higher but they also control the time
    very carefully. Some of the cracking people claim may be just due to
    grain growth by holding the metal too hot too long) Silver, copper
    and gold will start to anneal at about 200C ( Brepohl says higher for
    gold 400C) but this is not called for everywhere. Generally non
    ferrous metal can be quenched rapidly after annealing. This is not
    true for ferrous alloys which generally need slow cooling.. Know your
    metals. The best reference that is easy to buy ( except maybe for
    price) is : Brephohl's "The Theory and Practice of Goldsmithing" 

    http://www.ganoksin.com/jewelry-books/us/product/962596492.htm 

jesse
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