Sunlight and toning

[JIM F.]

Does natural sunlight affect toning on 90% silver coins? I have some dipped coins in my 9090 that I would prefer some toning...I know about the "taco bell" and smoke method, but wondering what if any effects exposure to direct sunlight might have.  Thanks. 

[BillJones]

It is my impression that prolonged exposure to sunlight will tone a silver coin. Question 1 is, will you like it? Question 2 is "how do you get it even on both sides?

[WoodenJefferson]

I would think you'd still need a source for out gassing, such as a sulfide contained in certain papers/card board/wood on or near the coin for acceleration in your lifetime. The sunlight would provide the heat to accelerate that process. Would a silver coin in a bell jar filled with inert gases sitting in direct sunlight tone? I don't know.

[BillJones]

I think that you are right about the heat speeding the toning process, WoodenJefferson.

[Conder101]

The only way sunlight is going to speed up toning is by making the coin warmer unless you are able to get a silver coin to react with chlorine or nitrates.  Many silver compounds are light sensitive especially silver halides but I don't believe silver sulfide is. (most tarnish is silver sulfide)  Silver sulfide is already black, the toning colors come from thin film interference.

[RWB]

Light is a form of energy and energy promotes chemical reactions which create the visible changes we call tarnish or toning. The OP can take it from there....

[physics-fan3.14]

The sunlight will accelerate toning because the heat makes the toning process go faster. It isn't "sunlight" that is doing it - any heat source will have the same effect.