complex chemistry on coin surfaces and conservation

[blakeyboy]

I found this thread on a minerals site, and it stuck me how similar it is to threads on this one!!

Maybe some of what these mineral collectors say is relevant to us?

If nothing else it's very interesting....

https://www.mindat.org/mesg-115692.html

Edited February 14, 2020 by blakeyboy
speling

[Mr T]

Hm, I hadn't thought about light-sensitivity.

Silver something-or-other was used for old photographic film or plates so that makes sense.

[Sword]

I think light can increase the speed of toning and that's the reason why some people leave cleaned coins on window sills. It makes silver reacts faster with gases in its vicinity.

Silver bromide was used in photographic plates. It darkens in light as it breaks down to give silver particles which causes a darkening effect. Not sure if this has any relevance to coin toning though. 

[Mr T]

I suspect not - just as silver nitrate I think stains the skin very easily but silver coins don't stain your hands.

[sabrejv]

I've found this paper on silver and light on the English Heritage site that may be of interest.

https://www.english-heritage.org.uk/siteassets/home/learn/conservation/collections-advice--guidance/effects-of-light-on-silver-tarnishing.pdf

 

 

[Sword]

Old established toning is safe. It is reassuring and has stood both the tests of time and light.