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<p>[QUOTE=&quot;Kasia, post: 1300550, member: 31533&quot;]Ok, I&#039;ve thought about it.....I don&#039;t know about the stream, but they may not be placing it in a stream as we think of one in the great outdoors, but simply a way of stating that the water the metals were immersed in (possibly to keep them from being affected by other mediums or particulates) were constantly refreshed so that particulates could not stay in contact with the metals. So I don&#039;t neccessarily think that tidal action would be what is going on. Basically trying to get an immersion medium that is as sterile and non-reactive as possible, so that the other variables would be the ones studied. Also, If one was done by day/night natural sunlight, then the light spectrum would include other than UV light, and necessarily be less illuminated by UV than a strictly UV light source for the other. </p><p>Probably you can&#039;t make a final judgement that is not questioned if you can&#039;t see the entire paper and see if the particulates that eroded from the metals due to light were measurably the same in weight that the metals were missing when the experiment was done. But I think that if this experiment was conducted in a manner as the abstract suggests, that it still seems like it either proves or strongly suggests that UV light by itself is damaging to metals. And it is not known whether it is UVA or UVB is the culprit, or if they work in tandem. </p><p>You do have a point, in that it is still possible that the UV light is simply a catalyst for action, whereby the action itself is only started and continued not by just the presence of UV light on an object, but by another object/item/particulate/whatever that is started and continued by the presence of UV light. But I don&#039;t have enough factors to say that UV light causing metal to displace from top to bottom (outer layers first) and excite the molecules of the metal would have or not have a lasting effect. In other words, maybe the excitement of the metal can, in periods away from UV light, relax to their &quot;original&quot; state, (or close enough) and not have a lasting effect if periods of rest from UV light is given. Maybe that is how the metals exposed to day/night were able to be kept seemingly intact and not affected, per a logical conclusion to reading that abstract. </p><p>And Southern California does have a wide variety of climates and conditions. Where I&#039;m at is a coastal/inland border, where some of the weather is more in the coastal type and other times the weather and conditions are quite similar to the inland conditions a few miles away. But even that is not so much the matter, as if you keep the coin protected (and not &#039;raw&#039; to the elements) you probably don&#039;t have that much factoring in. Say you encapsulate the coin in an air-tite or similar structure (which is not &quot;air tight&quot;). What you get is the air with the particulates that are in the air when you encapsulate the coin, that air and those particulates will always be in contact with the coin. So then, except for air movement exchanging into the container, at probably a very low rate, you have the sunlight with it&#039;s UV and other spectral frequencies affecting the coin surfaces that are exposed to it. That is also assuming you can control condensation inside and outside the display unit, which then would also get into the mix.&nbsp; So if you keep the house controlled for temperature and humidity it should be fine, excepting how it reacts with light or light reacting in context with what other factors you could not keep out of the mix.</p><p>I personally never intended to get this detailed about a subject that really for most coins doesn&#039;t matter a whit. Very few coins are so valued that you want to completely keep them in the dark as much as possible, in a non-reactive environment. And I firmly believe in looking at the coins I have in my possession. In fact, many times I have the coins raw either on my desk, or protected only in a flip or cardboard/mylar 2 x 2, which really only protects from handling. There is light in and around my workspaces, so my coins do get light on them. But I don&#039;t have very many really valuable coins. I recognise that the way I work will allow light to get at these, but it is minor. Still, the primary answer to the question is that light is detrimental to coins, whether by being the catalyst or by itself. And toning can occur in a home, simply by putting a coin on a reactive type surface and allowing the air currents in the home to do their work. </p><p>If these coins are not his &quot;precious&quot; then why worry about exactly how long or with what certitude damage will occur to a coin. Just enjoy the little buggers. It&#039;s just that his question wasn&#039;t should he display them, but would light affect coins. It&#039;s his choice whether to display them.</p><p><br /></p><p>Bottom line, enjoy your coins....it&#039;s a hobby.[/QUOTE]</p><p><br /></p>

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