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Posted (edited)

I was surprised to see some of the things the British Museum are doing to their coin collection. Here is 2 treatments undertaken on an Ormonde issue civil war Irish crown.

Treatment date

3 May 2000

Treatment proposal

Light clean and lacquer where necessary.

Condition

Light, surface coating of dust and tarnish. Surface changes with a dull, matt appearence due to conversion of silver chloride to silver.

Treatment details

Cleaned using Acetone (propan-1-one/dimethyl ketone) applied on a soft brush. Lacquered with a 5% solution of Paraloid B72 (ethyl methacrylate copolymer) in 50;50 Industrial methylated spirits (ethanol,methanol) and Acetone (propan-1-one/dimethyl ketone) applied with a brush. This was done to help prevent further conversion of silver chloride to silver.

Treatment date

9 September 1996

Treatment proposal

Clean coin

Condition

Dirt and grime covering a heavy silver sulphide corrosion layer.

Treatment details

Swabbed with IMS and Acetone. Lightly polished with Goddard's long term silver cloth (comp. unknown).

Edited by Nicholas
Posted

And ... here's the result:

AN00105805_001_l.jpgAN00105806_001_l.jpg

Not quite as bad as one might imagine from the description!

My Father-in-Law sometimes asks why I don't visit more museums as 'surely they have the best coin collections'?

Despite my explaining that museums seem to have different aims and often end up with a random selection of donated items they want to look nice, rather than a proper collection that can be used for study and comparison, I'm not sure he gets it ...

Posted

Yes Tom, I hope the restorers didn't accidentally put that hole in the coin...

Posted (edited)

Oh yeah the holes don't match. I can definitely see some residual silver cleaner in rim devices! And an uncertain lacquery shine ...I recall two Carlisle siege shillings sold in a recent spink auction with similar characteristics...

Edited by Nicholas

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