The E-Sylum:  Volume 9, Number 15, April 9, 2006, Article 25

ANCIENT COUNTERFEITERS COULD HAVE USED FIREGILDING TECHNOLOGY

Dick Johnson writes: "It is understandable an ancient coin that
appeared silverplated would raise many questions (as noted in last
week's E-Sylum). The process of electrolysis was developed by a
German physicist and engineer, Moritz Herman Jacobi (1801-1874),
in 1837. He called his process "galvanoplasty" and it led to the
fields of electroforming and electroplating (great for the
silverware industry).

The process required an electric current, so from 1837 until 1890,
when electric generation became available (thank you Thomas Edison!),
it had to be accomplished with primitive batteries.

There was a technique that could have been used this early. It was
the technique of "firegilding." The ancients knew how to coat an
object with gold by using mercury. They could have accomplished this
with silver just as well (but I have not heard of the term
"firesilvering" nor have I heard of such an object). [Museum
Curators Note: Please prove me wrong that such a silver-coated
object DOES exist, particularly before 1837.]

The process shorted the lives of those who did firegilding. The
mercury fumes are deadly. I'll describe the process, but don't
try this at home. [Official Disclaimer – We Are Not Responsible
If You Are Stupid Enough To Try This!]

You need a "gilding stone" a flat surface like marble will do.
You need gold, mercury, a brass brush, nitrate of bioxide of
mercury and a stove. That's all. Shortly before you do this, mix
the gold and mercury together, it becomes waxy between the fingers.
Make a ball and place this under water until use. When ready take
the ball and rub all over the gilding stone until it covers a
large spot.

Dip the brass brush in nitrate of bioxide of mercury. Rub the
brass brush on the gilding stone until the mercury-gold is deposited
on the brass bristles. It will be white in color. Then brush the object
to be gilded with the brass brush. It will take considerable brushing
to get an even deposit of the mercury-gold on the object (well cleaned
and degreased). Then heat the object. The mercury fumes will burn off.
Don't get anywhere near these fumes – they will kill you!

The gold is left on the object. Several applications may be necessary.
It is not a thick coating like goldplating. The thin coating is
susceptible to wearing off, particularly on the highpoints. In later
years firegilt objects may have an uneven gold color (with dark areas)
and sometimes only left in the crevices of the relief. This gave rise
to the term "parcel-gilt" which may have been intended (only a portion
of the relief with gold) or a result of wearing off.

The ancients could have done firesilvering by suing silver instead of
gold. Renaissance medals frequently show evidence of firegilding.
Japanese had a similar process where they gilded sword guards – tsuba
– 400 years ago.

In America, firegilding was done as early as 1820 by Scovill
Manufacturing (there's that name again!). They used this process
to coat with gold, silver, copper and zinc but converted to
electroplating entirely by 1844."

[You never know which E-Sylum item will trigger an interesting
response from one of our readers.  Leave it to Dick Johnson to
provide us with background on another fascinating aspect of
numismatics and minting technology.  -Editor]

  Wayne Homren, Editor

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