[Jewelry making - Article 00859] - [Orchid] Tarnish problems while tumbling

[jonathan presson]

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    I'm new to this group so first let me say hello...... 

    And now for the questions.... (let the games begin): 

    I've been working on some mass finishing issues for tumbling glass
    and metal at the same time in order to eliminate hand finishing of
    pieces. 

    needless to say I am having some problems.... when tumbling with
    plastic media from Rio the glass gets slightly abraded, no problem as
    this is easily refinished using a lap wheel and cerium oxide, brings
    the glass back up just fine unfortunately some of the cerium oxide
    gets trapped behind the glass pieces.... this in itself is not a
    major problem as we are using primarily opaque glass pieces so it is
    unnoticeable.... 

    however, when I return the pieces to the tumbler to burnish the
    silver using mixed stainless shot and Rio deburring solution... there
    seems to be a chemical or electrical reaction occurring that is
    causing oxidation on the surface of the silver on testing the
    solution after tumbling I get an approximate PH of 8 

    anyone know exactly what's going on.... I have the funny feeling
    that the cerium is acting as an O2 donor for anodizing the
    silver..... could this be the case.... and if so anyone got any
    suggestions on how to eliminate this issue 

thanks,
Jon P

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