Bjorn
There are two variants of mercury gilding. In the first the surface of
the metal object is cleaned, rubbed with mercury (mixed with either
powdered charcoal or chalk, according to different sources) to produce a
mercury-rich surface and then the gold-mercury amalgam is brushed,
rubbed or pressed on. The object is gently heated to drive off the
mercury and the gilded surface can then be burnished to give a shiny
finish.
In the second, the surface of the metal object is also cleaned, rubbed
with mercury to produce a mercury-rich surface but then gold leaf is
laid over it. Heating drives off most of the mercury, leaving the gold
bonded to the underlying metal. If the bulk metal was not clean enough,
or insufficiently amalgamated, the bond would not be good and flaking
might be the result.
If you have detectable levels of mercury in the gold surface, it is
almost certain that it was applied using mercury gilding.
Justine
Dr Justine Bayley
English Heritage
Fort Cumberland
Fort Cumberland Road
Eastney
Portsmouth PO4 9LD
Phone: 02392-856794
Fax: 02392-856701
Email: [log in to unmask]
-----Original Message-----
From: Arch-Metals Group [mailto:[log in to unmask]] On Behalf Of
Bjorn Hjulstrom
Sent: 07 December 2006 11:35
To: [log in to unmask]
Subject: gilded viking age pendant
At an excavation of a viking age mound in middle Sweden I found a gilded
pendant. When I discussed the gilding with collegues we cannot agree on
the method used and I was recommended to try this forum.
Before I describe the pendant I must appologize that I do not know all
the
correct terms in english but I think I can make myself understood
anyway.
The material of the pendant is silver. The gold surface consists of ca.
80%
Au, some other elements and 4%Hg. The mercury implies that the it was
gilded using heat to unite with the silver. However, when looking at the
pendant it seems at it is some kind of gold leaf. The gold is clearly
separated from the silver and at some places it has come off as gold
flake.
So the question is what technique was used. Can gilding including heat
still making the gold peel off because of it was only uniting with the
surface of the silver, wich possibly was not clean. Or is it possible
that
some kind of gold leaf was used and pressed on to the pendants.
I would be grateful for comments.
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