Cleaned or not?

[ozjohn 746]

Attached picture is of a 1911 proof set as advertised by Coins and Medals, Brisbane. As you can see the coins are toned after being left somewhere possibly over a hundred years. This is the condition I would expect to find coins of this age to be in. However the amount of coins for sale of a similar age that are bright makes me wonder how they remain in that condition over a similar age as with the 1918 half crown?  Anyone who has silver objects will note the only way of keeping them shiny is frequent cleaning

Perhaps it may be useful what toning of silver is. It is the equivalent of rust on iron and steel. In other words corrosion where silver metal is attacked by the oxygen and sulfur in the atmosphere to form oxides and sulfides of silver.

Some will argue that toning is attractive and I am sympathetic to that view but not all toning is of that nature. Again the colors produced by toning are as a result of constructive and destructive interference where the incident and reflected light interact with each other.

Again I still wonder how silver coins retain their shiny status? Some coins certified by TPGs as cleaned while some it is obvious due to signs of abrasion while others I have been stumped by this verdict. Having said that I can only make that judgement from the photographs of the coin and not in hand.

[VickySilver 910]

Yes, always seem to be a subjective component to this sort of thing. BTW, nice reverse on the 1918 and maybe excellent lustre in hand.  Also the first photoed set is a bit ugly and possibly not in the range of restorable. I have found paranthetically (sp?) that dilute clear ammonia with liberal rinsing afterwards often does a nice and believable job of surface restoration....

[ozjohn 746]

7 hours ago, VickySilver said:

Yes, always seem to be a subjective component to this sort of thing. BTW, nice reverse on the 1918 and maybe excellent lustre in hand.  Also the first photoed set is a bit ugly and possibly not in the range of restorable. I have found paranthetically (sp?) that dilute clear ammonia with liberal rinsing afterwards often does a nice and believable job of surface restoration....

Are you talking about clear household ammonia for cleaning that seems to be 25% ammonia  or further diluting this product? With regard to your comment the 1918 half crown is a very nice coin but I struggle to accept it has remained without any sign of toning after over a hundred years.

Edited May 27 by ozjohn

[VickySilver 910]

I agree, the surfaces "conserved" of oxidation - generally known in chemistry as reduction reactions.

We have differing solutions of ammonia, the 25% would probably be alright. Please do experiment with lesser value pieces and suggest that they be of higher grade though & suggest all finenesses of silver and limited exposures on copper nickel as longer may start to dull lustre. 

[ozjohn 746]

4 hours ago, VickySilver said:

I agree, the surfaces "conserved" of oxidation - generally known in chemistry as reduction reactions.

We have differing solutions of ammonia, the 25% would probably be alright. Please do experiment with lesser value pieces and suggest that they be of higher grade though & suggest all finenesses of silver and limited exposures on copper nickel as longer may start to dull lustre. 

Before and after using cloudy ammonia that I had to hand. Cloudy ammonia in Australia is 25% with detergent added. I think it has improved the coin marginally but it has removed the green verdigris by the G in GRA. The coin looks better in hand but a very light strike. When I did chemistry at uni it was called Redox, Reduction, Oxidization depending on which way it was going.

Edited May 27 by ozjohn
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[Peckris 2 2,239]

I've bought silver that was so shiny that some dealers avoided it like the plague. However, I have a nearly infallible way to tell : if the shine is in the fields and between the legend, but not on the design or legend, then I judge it’s natural; it would be virtually impossible to clean only the parts that exclude all the raised elements. As to how they survive in that condition, I wouldn't like to speculate.