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BOOK IX
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189
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lar
leaves three-quarters of an inch wide are made from the thick gold
plated sheets. These leaves are fastened to bands and worn around the
head by young girls. Thin sheets are not used in the third method of
plating silver. Quicksilver is used and although the method was known
to Pliny he did not describe it. Today the following method is used. An
eighth of an ounce of gold that is quite pure or contains only a very
small amount of silver is beaten out into a thin foil three inches long
and two inches wide. After the foil is cut into small pieces and placed
in a crucible three-quarters of an ounce of quicksilver is added. The
mixture is poured into another crucible lined with chalk and then
heated over a charcoal fire. It is placed in the fire with a pair of
tongs and left until all the gold has been dissolved in the quicksilver
and no flash of gold can be observed. When finished the quicksilver is
poured into the shell of a marine scallop that has been filled with
water. After it has cooled the water is poured off and the quicksilver
left in small particles similar to wheat meal and can be picked up with
the fingers. This is then spread over the silver object that is to be
plated using an iron instrument. Before applying the quicksilver, the
silver object is heated in a charcoal fire and quenched in water in
which argol and salt have been boiled in order to make it white. After
this it is cleaned by brushing with brass wires that have been bound
together, although it has already been cleaned by quenching. After the
quicksilver has been applied the object is exposed to the fire a second
time so that it will take the mixture. During the heating the mixture
is spread evenly by brushing it with pig bristles that have been bound
together. Eventually the quicksilver is driven off by the heat of the
fire and the gold remains. If any part has not received sufficient gold
more quicksilver can be added to the area and it is heated and brushed
a second time.
Copper and brass can be gold plated in a similar manner. Iron and the steel the Greeks call στόμωμα, as
I have said, is first polished and then smeared with wine in which has
been boiled one part of argol, one-half part artificial sal ammoniac,
one half part verdigris and a little salt. Usually it is brushed with
pig bristles that have been dipped in the wine. After drying it is
plated with the same mixture of gold and quicksilver, using the same
method as that for copper and silver. Enough concerning gold plating.
Copper
and brass are silver plated in the following manner. Argol, alum, and
salt are first ground to a powder. Then thin silver foil is ground on
flint with this powder and the mixture placed in a jar that has been
coated with litharge or molten lead. After water is added the article
to be plated is placed in the mixture and the jar warmed. After warming
for some time the article is removed and brushed with pig bristles to
determine if it is plated satisfactorily.
One metal is coated with another metal in the following manner. Copper, brass or iron that is to be coated with silver, stannum, stannum argentarium, or tin, is first rubbed with vinegar in which artificial sal
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