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Re: [Orchid] Pits in sterling silver
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Debra Hoffmaster Wednesday, November 08, 2000
   
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To all -


>     Sounds like there may be a combination of problems, one of which is
>     Overheating . . . you also neglect to tell us what kind of solder
>     you're using.  The kind of solder may be another problem. 


    Oops.  The solder I am using is sheet solder cut into bits.  It was
    purchased from Rio Grande. 

    I may be overheating, but the problem only appears when I use the
    prips flux, never when I use boric acid in alcohol.  I believe that I
    solder in the same way using both approaches. 

    and Timothy Hansen <tahhandcraft AT earthlink.net> asks 

>         Is it possible that you have a contamination problem? Have you
>     used any low temp alloys such as pewter or any tin, lead bearing
>     alloy? If so make sure that your work area and soldering area are
>     cleaned thoroughly. 

    Tim - yes, I have used pewter, but never in my shop, only as a
    demonstration at shows or schools.  Also I have never used my own
    tools on pewter. However, the silver sheet that I  am currently using
    came to me via the death of another silversmith and I do not know of
    the conditions in his shop.  However, I do clean my metal before using
    it.  I am currently cleaning it with a tuffy plastic pad.  Could
    residue of plastic be causing the pits? 

    text of origonal post follows Hello all - 

    I am a hobbyist who has been subscribed to the list for about a year.
     I have learned many useful things here and I greatly appreciate the
    service that all of you provide by sharing information through Orchid. 

    Recently a problem has developed that I hope you may be able to help
    me with.  I have begun getting pits in sterling silver that I have
    coated with Prips flux.  I am using using acetylene + air to solder (a
    prest-o-lite).  I use Prips flux as an anti-oxident and use Battens
    flux at the joints.  The pits do not develop in the joints, but rather
    on the exposed surfaces of the sterling.  I was pickling in pH down,
    but switched back to Sparex in case that was the problem.  It was not. 

    I also stopped cleaning my metal with steel wool and switched to a
    nylon pad in case that was the problem.  It was not. 

    I mixed up a large batch of Prips flux about a year and a half ago. 
    I used Peter Rowe's formulation (1qt water, 120gm Boric acid, 80gm
    trisodium phosphate, 80gm borax) and stored it in a glass chemical
    bottle with a bakelite lid.  The flux was stored, in my shop, at
    between 65 and 68 degrees F.  Over time, solids have precipitated out
    of the solution and have come to encrust the bottom of the bottle. 

    I have tried several dispensers and the most dependable one I have
    found formerly housed "Revitalique daily protectant," which is a hair
    care product containsing collagen, protein and sunscreens.  The bottle
    was thoroughly washed before the flux was added.  The plastic of the
    bottle is labelled #1 - PETE. 

    Initially, there was no problem in using the Prips flux.  The pitting
    has developed only in the last month or so which is why I thought it
    might be due to my switching from sparex to pH down.  Unfortunately, I
    am at a loss to isolate the problem.  I am, however, assuming that the
    precipitation removes all components of the flux equally; producing a
    weaker, but still equally-proportioned (3:2:2) flux.   A recent post
    suggesting that the order of applying borax and boric acid separately
    could matter has prompted me to wonder if the precipitation has changed
    the proportions of the flux. Anyway, as there are many variables here,
    I am asking someone wiser than I to direct my search for a cause. 

    Finally, when I use the prips flux, I apply a light but even coat of
    liquid and gently heat the metal until the water evaporates leaving a
    white coat over the surface. Under heat, the prips becomes clear and
    then red (?).  Is this correct?  It seems to me that it used to turn a
    sort of brown color.  Finally, the areas with the pits are often
    associated with a greyish, glassy buildup of the flux. 

    I am sorry this is so long, but I'm not sure what information is
    really important.  I look forward to hearing your advice. 

    Cheers & thanks Debby Hoffmaster in sunny 70 degree Michigan
    dhoffmaster AT tc3net.com  



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