[Jewelry making - Article 00253] - Re: [Orchid] Twenty MuleTeam Borax

[coralnut]

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    James, I am sure the following is of no surprise to you but I wish
    to reiterate it for our audience. 

    Borax is comprised of a group of the borates including: 

    Sodium tetraborate - an anhydrous sodium borate (Na2 B4 O7) contains
    little or no water that melts at 741 deg C (1366 deg F) 

    Sodium Tetraborate decahydrate - a hydrous sodium borate (Na2 B4 O7
    *10H2O) contains water and melts at 75 deg C (167 deg F).
    Tetraborate decahydrate can be dehydrated by heating to 120 deg C
    (248 deg F).  It will lose all water when heated above 320 deg and
    fuses at 740 deg C, 

    Knowing that,  I find it difficult to understand the results of your
    experiments when there are finite conclusions re the melting points
    of specific varieties of Borax. True, there is a wide range of Borax
    products available but generally speaking, commercially sold borax
    is usually the dehydrated variety, i.e., the anhydrous type which
    has a high melting and fusing temperature. At high temperatures,
    borax has a strong solvent effect on metal oxides and related
    materials. Believe it or not, I do hot have a copy of Dr Bephrol's
    book in my 200 or so book library. Perhaps Charles and/or Tim could
    provide some further information or maybe John can chime in from
    down under? 

    Boric acid is yet another question mark. Boric Acid (H3 BO3) aka
    orthoboric acid, is refined borax that dehydrates above 170 deg C,
    melting at 171 deg C to form metaboric acid.  Metaboric acid, in
    turn, melts at 236 deg C and further dehydrates into tetraboric acid
    above 300 deg c. Each providing its level of protection to the metal
    surface. So its decomposition is well below the more common
    tetraborate variety of borax. 

    Comments? Cheers from Don at The Charles Belle Studio in SOFL where
    simple elegance IS fine jewelry! dcdietz AT comcast.net 


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