When I was teaching in Bali, the local jewelers were using a peeled
lemon with a bit of salt in the mixture for their pickle. I have
been experimenting with home made pickles ever since. I have found
that 1 cup hot lemon juice with 1 teaspoon of salt or 1 cup of hot
vinegar and 1 teaspoon of salt make a wonderful pickle for Argentium.
Hi Ronda,
Quick question re. your post - how does this pickle seem to work
with a combination of metals on a piece such as argentium and
regular sterling or gold?
Organic materials like lemon juice, vinegar, orange juice etc have
been used since the discovery of how to smelt metals. Sulphuric acid
can be made by decomposing iron pyrites, if anyone knows how the
ancients made nitric acid I would be interested to know as it isnt
recorded. Agricola has chapters on it and much of his work is based
upon activities that hadnt changed by the 1500’s from ancient times.
I have assayed metal by cupellation but only to demonstrate it. Along
with many old techniques for determining ore minerals and secondaries
the techniques have died out in a generation. Does anyone know if
flame analysis using a blowpipe and carbon block is still used in
earnest?
Nick Royall
I have assayed metal by cupellation but only to demonstrate it. Along with many old techniques for determining ore minerals and secondaries the techniques have died out in a generation.
Cupelation AKA fire assay is still widely used, it is more accurate
than XRF and way cheaper than Atomic Absorption.
James Binnion
James Binnion Metal Arts
I know that the UK assay offices still use fire assay in some
circumstances. As for nitric acid, Cellini also gives some discussion
to it, although nothing as detailed as Biringuccio in his
’Pirotechnia’. The origin of the acid, along with a few others, was
in the Middle East in the 8th century, by an “alchemist” called Jaber
bin Hayan, but whether it was used for assay at that time is unknown
to me. I don’t think the strong acids became common in Europe until
much later, perhaps as late as the 16th century.
Jamie Hall
Laser ICP seems to be the most common method used by assay offices in
the UK, used to be by cupellation and titration for silver but that
needed more skilled people to do wheras the ICP can be set up and run
quite happily by 1 person and then left alone to get on with a batch.
I know that they teach assaying in the mining courses in universities
in Australia but wondered if this was carried on into “the field” so
to speak.
Nick Royall