Hi David,

Silver is not affected by light to any significant degree. The
blackening of silver, known as tarnish, is caused by a reaction of
silver with hydrogen sulfide in the atmosphere, producing silver
sulfide which is a dull grey or black film o the surface. Silver can
also degrade with oxygen over time, but it is a very small effect.
With so many sulphur compounds in the air, and especially in the
industrial era, this is a problem. Varnishing silver leaf obviates
tarnishing. So, no, oxidation of silver is not the same thing as
tarnish. It's a good question.


Andrew


On 16 February 2016 at 12:11, Kelzenberg, David C
<[log in to unmask]> wrote:

> Is not silver tarnish caused by exposure to light, rather than air?  Does the varnish in some way prevent a certain band or color of light from penetrating, thus preventing tarnishing of the silver?  (Is "oxidation" in silver the same thing as "tarnish?")

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