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Thank you all for your speedy and highly knowledgeable responses. I'll take comfort from what you've said, suffice to put the wire wool and abrasive paper away!

Vicky, if the purple palm prints are skin oil, is it possible to clean it off without damaging the coin or will it have reacted or etched itself into the surface?  Sorry to be a nuisance but my mentioning wire wool and abrasive paper is a good indication of my complete lack of knowledge on the subject!

Thanks again

Cliff

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I have never been shy about good acetone and a quick tamp down.  Problem is that the skin oil is,as I understand it, breaks down by bacterial action with organic acids that oxidize the surface metal. 

Still worth it as some of the oil and metallic compounds that are generated can be removed, some even after longer exposures....the metal underneath is usually not terribly altered. 

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3 hours ago, VickySilver said:

I have never been shy about good acetone and a quick tamp down.  Problem is that the skin oil is,as I understand it, breaks down by bacterial action with organic acids that oxidize the surface metal. 

Still worth it as some of the oil and metallic compounds that are generated can be removed, some even after longer exposures....the metal underneath is usually not terribly altered. 

Thank you Vicky, your advice and prompt replies are much appreciated.  I'll have a go on a small area with acetone and cotton buds to see if I can bring about any improvement.

Cliff

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NO RUB, please.

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22 hours ago, VickySilver said:

NO RUB, please.

Update - don't know if my cleaning attempts did any good but don't think I'll try anymore.  There is some pitting within (because of?) the stained/flecked area but, as with the flecking and purple stain, hardly noticeable in hand under natural light.  Other than these 'metal defects?' the coin detail,fields and rims are high grade, even taking the 'pothole' by the trident handle into consideration.

 

Close up, after 'cleaning', attached.

1849 3 REV TEST.jpg

1849 7 Rev TEST.jpg

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Point to ponder: Came across this other example of 'purple sheen' under scope light.

Circular patch on Vici's cheek appears to have a distinct edge.  The purple sheen around her mouth seems to emanate from the circular patch by her mouth  Wonder how the verdigris ties in?  

1851 Purple Close.jpg

1851 Purple Obv.jpg

1851 Purple Rev.jpg

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Wow, nice pictures there. On the 1849, the colour appears to be metal oxidation - too late for organic solvent rescue. I agree, have to leave it alone but at least you tried. 

The second piece almost appears as though some liquid dropped on surface with secondary oxidation. 

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1 hour ago, VickySilver said:

Wow, nice pictures there. On the 1849, the colour appears to be metal oxidation - too late for organic solvent rescue. I agree, have to leave it alone but at least you tried. 

The second piece almost appears as though some liquid dropped on surface with secondary oxidation. 

Thanks for all your time and trouble Vicky, not to mention your willingness to share your knowledge.  Reckon I owe you a beer.

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5 minutes ago, Cliff said:

Reckon I owe you a beer.

Flight to the US - £500. Beer - $5. Have a couple and make the trip worthwhile.:mellow:

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