Pickling
Silver
This
term relates to the removal of firescale from silver by use of
chemicals, often slightly warmed.
When
heated, silver blackens on the surface. It is common in
silversmithing to pickle the object, bringing the shine back.
There
are several methods.
Hydrochloric acid is the most common chemical used. It normally is used in
concentrations of 10% or less and often is slightly warmed in a soup
warmer or other similar temperature controlled container
Hydrogen
peroxide (sparex) solutions can be used, but are a bit slower. This
also is used in a soup warmer.
Acetic
acid, available from most chemists and home-brew suppliers, can be used
but is so much slower that significantly long soaks are required.
The best solution for this is a 5% solution of citric acid or similar concentration of tri-sodium citrate. This latter is best for glass, as it chelates the corrosion or stuck kiln wash, but does not etch the glass even after 48 hours soaking.
Revised 6.1.2022
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