To all,
This is from the book “The Metalurgy of Gold” by Sir T.K. Rose who
was knighted for his work with the English Mint regarding gold and
it’s chemistry. His book was published first in about 1896 if memory
serves me correctly…
There is a reason I didn’t post to all and it is called liability
law. Okay so a disclaimer I suppose first. If you burn your pinky or
your big toe or some other part of yourself I am not to blame. Okay
here it is and believe me it really does work… Be careful because
the solution needs to be heated to near boiling hence the
disclaimer.
Take a pyrex beaker or an old pyrex coffee pot add a couple of pints
or so of hot tap water and mix 1 tablespoon of Potassium Nitrate
(Saltpeter is the common name) which you can get at a drugstore with
two tablespoons of non-iodized table salt and one teaspoon of alum
(this is found in the spice section of the grocery for use in canning
pickles).
Put your jewelry item without stones (ruby or diamond or hard stones
are okay to put in the solution but avoid putting malachite or lapis
or similar softer cabs in this stuff) Heat the solution with the
jewelry in it for an hour or two on a hotplate adding more water if
necessary.The best temperature is just below the boiling point of
water or about 190-200 degrees F…This solution works well on
sterling silver also by the way.What this does is dissolve the base
metals near the surface of the item leaving a fine gold or fine
silver outer layer.Rinse well with hot water and polish with a soft
cloth. I usually polish first with rouge and clean the item with
ammonia and then use the solution.
This method was used widely in France before electro-plating became
common. It is much safer than plating with cyanide solutions and the
finish is every bit as good. (For those who are new to jewelry
making it is common for some shops to plate even gold articles after
soldering to cover discoloration particularly on articles with soft
solder which often leaves a gray color around the solder joint.
Treatment with boric acid and denatured alcohol prior to soldering
usually holds any discoloration to a minimum though.)
Remember to wear the standard protective clothing for handling
chemicals, rubber gloves, apron, eye protection and sturdy foot wear
with high tops.
This solution will keep for a long period and can be re-used. If it
seems to weaken add a bit more alum or saltpeter or table salt. If
your water is heavily chlorinated it is not a bad idea to buy
distilled water since chlorine does have the ability to dissolve
small amounts of gold although it is very slow at doing so. Iodine
also has this capability of dissolving gold in small amounts and that
is why I recommend non-iodized table salt for this purpose.
hth…