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Sterling contaminated with pewter


#1

Is there some chemical way that we can remove what is probably pewter
contamination on an almost completed repousse piece of sterling
silver. The small pits appeared after annealling and pickeling, and
it would be great if someone has the knowledge to share so that we do
not have to give up on this incredible piece of work and the many
hours already invested in it

Hopefully, Alison and her cohorts in beautiful Mud Bay where it is
the best sort of clear autumn day (before the rains set in)


#2
    Is there some chemical way that we can remove what is probably
pewter contamination on an almost completed repousse piece of
sterling silver. 

I am unable to answer your problem directly - other than to say that
I very much doubt whether there is any suitable chemical treatment.
But would it be possible to drill out the pits with drills a little
larger than the pit, then carefully fit plugs of sterling, silver
solder them in place, then sand away all the excess metal of the plug
right back to the original metal thickness.

I don’t know, but it might be worth your while to try it out on a
piece of the same thickness scrap, to see how it looks after proper
sanding and polishing

  •   John Burgess;   @John_Burgess2 of Mapua Nelson NZ  where
    

daffodils , bluebells and kowhai blossoms have gone, cherry and apple
blossoms are going, and the nights are getting shorter - and warmer.


#3

I have see recipes in old books for removing lead or mercury from
gold with oxalic acid. Does anyone know of this method? Perhaps it
would work for removing the tin/antimony of pewter from silver.

David L. Huffman


#4

Don’t heat it to take it off…it will eat and combine with the
silver leaving large holes…the only way to remove lead is to
oxidise it… this is a process that can be obtained from a
metalurgy book… i have always ground the piece till clean and
used a low melting point solder to build up the back after ward…{any
residual lead will combine with the low
flo point solder}… not sure of any other method…ringman


#5

Removing Pewter from Sterling might be done by using concentrated
Acetic Acid (glacial) applied directly to the area of contamination
with a glass dropper. I remember that Lead and Tin acetate are quiet
soluble in water.
ROBB


#6

Whenever we have gotten a small amount of tin solder or lead solder
on a sterling silver piece, we put the item in the pickle pot for a
couple of hours @ 180 oF and the solder dissolves off the item leaving
a slight grey color that is then fiberwheeled or sanded off and then
we would repolish the piece. Also, A mild nitric acid solution would
probably work.

Daniel Grandi http://www.racecarjewelry.com Casting and finishing
in gold, silver bronze/brass and pewter for people in the trade


#7

Hi, Daniel. I would be afraid the nitric acid would dissolve the
silver. Margaret


#8

Surface contamination by tin could be removed using hot strong
hydrochloric acid. There is significant danger in doing this, and
you would need to take suitable precautions.

But in this particular case it sounds as though the tin has really
got into the silver during the annealing. Probably the only thing to
do is to physically remove the contaminated and pitted material, by
drilling or scraping. If it is only on the back, and there is to be
no more heating, may be best to leave it, if this is ethical/legal. –
Kevin (NW England, UK)


#9

Pewter can be removed from sterling silver by using hydrochloric
acid. This will etch away the pewter without harming the silver. Just
put the pc. in and watch it bubble away. CAUTION!!! DON’T BREATH THE
FUMES. Use Open ventilation.

Raymond Cutuli www.triosilversmiths.com
repairing replating refinishing, Tea sets,candelabra,antiques