Displaying Coins and Sunlight

The study I referred to is one that was done with same conditions of water - one in UV light and one without UV light, so that the only variable involved in having MORE corrosion is the UV light. I am not saying that the water immersion did not have any effect on the metal, but that the UV light caused the metal to have more corrosion than the same metal immersed in water did without UV light. That is why they refer to it as photo-corrosion. Whether the UV light would have done that without a water base or whether it was done more because it was combined with the effects of water, it still stands that more corrosion happened in the milieu of UV light.

 

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That's cool. Now you have the problem that ordinary glass window allows almost no light in the UV spectrum to pass. So, you need a study that looked at other wavelengths of light to be relevant to the question at hand.

 

[h=3]UV light is divided into two types UVA and UVB. Both have an effect. And window glass blocks only UVB but lets up to 75 percent of UVA through. Tinted and reflective glass still allows about 25-50% to pass. Laminated glass and UV-blocking coated glass both filter out from 95 to 99% of all UV light. Neither is common in residential or commercial structures. Laminated glass, made of two layers of glass with a plastic layer in between, is used in some public buildings, such as airports and museums; it is also used for automobile windshields. [/h]
So, unless you are willing to go out on a limb and say that all UV light damage is caused by the UVB side, then just having glass will not filter out the damage.

 

What good is a collection if you can't have them out because of the light, or whatever particles are in the air they are exposed to (yikes!) What do you do, take a flash free picture, and then just look at it once in a while? Perhaps it depends on what type of collector one is..preserving for the future or having them for your own enjoyment.

I display in a curio all those that I like to actually see. And I suppose they'll rot. After reading this thread, I'll surely rethink my display.

My real beauties are (sadly) in a safe or sdb.

Not sure I'm glad to have learned about the light exposure here...

Lucy

 

I think being a collector you will have some damage to the coins just by having them out and looking at them, but you just have to minimize it, since absolutely nothing remains the same over time. Barring some unforseen disaster, I'll be long gone before my coins (being handled as items I enjoy looking at) deteriorate due to UV light or other environmental hazards. If you keep the coins as well as you can then they will be there for you to enjoy. Whether you've taken good enough care of them for them to be enjoyed generations from now in the same state you currently have them is a different story. And no one will know if their collection will stand the test of time. That measurement can only be seen looking from the future to the past. So displaying the coins in a manner that is pleasing to you is important, even if it does affect the coins. If your coin is important to you to display for you to enjoy, then display it in the manner you want to. Just be aware that you may choose a display that inadvertently mars your beauty and it may not be what you want years from now. If it's more important to you to "keep it safe" from harm, then take pictures of it, protect it as best you can, and enjoy the pictures.

I think that there are more harmful things to coins than the artificial lights or natural light allowed in the house --- unless you deliberately place coins in sunlight for extended periods of time. And I agree that placing coins for display in visible areas give more chance for someone to think they want to take it.

But, bottom line. Science can prove light hurts objects, but if the only way you will enjoy the coin is if you place it in light, then by all means do so. Just don't expect the coin to remain pristine over time.

 

First off, the coins are in a backyard facing window. The only way they're visible to a stranger is if that person has already climed the wall with malicious intent anyway. (give me a little credit, I'm not quite *that* dumb )

I am definately in the group with the oppinion of "what's the point of having a collection of shiny pretty things if the only way you can see them is to drive to the bank to open your safe deposit box?"

So then, if I accept the statement of:

But, bottom line. Science can prove light hurts objects, but if the only way you will enjoy the coin is if you place it in light, then by all means do so. Just don't expect the coin to remain pristine over time.​

The question then becomes: what time frame are we talking about when we say 'stay pristine over time'? I figure its pretty clear that the coins won't be visibly different after a few months. Are we talking years? Decades?

 

Are you certain of this? I'm pretty certain you're wrong. Chemiluminescence is an exothermic chemical reaction. You don't "feel" heat because the energy is being released primarily as light over an extended period of time. There is heat produced. It's just limited.

Also, fireflies use bioluminescense. The broader "umbrella" is merely luminescence.

 

The answer depends upon where you live, what type of pollution is present in your area, etc.

 

SoCal Suburbs

 

Two points: 1) That's not my question. And 2) The fact is I don't believe that "its pretty clear that the coins won't be visibly different after a few months".

To me it doesn't matter when discussing the effects of light on coins whether the time frame is able to be clarified to any particular time in days, months, or years. The fact is that when a circumstance like light, or any other environmental condition having a cumulative effect on something, their generally is no "visible" point where one can say that's enough, I won't go farther because if I do, then there is irreparable harm. The harm is already there, it's just you don't know where the tipping point is. That is the crux of the matter as far as I am concerned. Whether the coins you place at the window will turn a month or a year or ten years on is not really any point of this at all. The coin has been damaged, even if you can not "visibly" see it. It may only be damaged to the point that any other condition you place on it that is harmful may act faster on it to corrode it than it would have if it had not been in the light. In other words, it is "hidden damage".

Also, you were asking for other person's opinions on this and I gave you mine, and I backed mine up with scientific data to support what I was saying. I never intended to be able to give you an exact timeframe when you could tell (assuming you put your coins in light for display) when it would be "apparent" (i.e., visible to the human eye, whatever that is, based on a person's eyesight and ability to differentiate between what it was before and what it is now, after time has passed) that there was a change.

I basically tried to leave it that it really is up to you as a collector/enjoyer of coins whether you want to do that to your coins.

You posted:

I answered that. And my answer was yes, it would. You are the one who will have to ask yourself if, based on the information you have, whether you want to display your coins in light. Only you can answer that question. And if you want to know more, then you should search out the information yourself.

 

I know people are trying to be helpful, but this thread has become as if the OP asked if he should display a 1913 Liberty Nickel in direct sunlight with a slight mist of salt water constantly blowing over the coin. C'mon guys. It's some silver and a little gold. After reading all replies again, I say put them on display to enjoy. If you were displaying a 1933 Double Eagle or a 1913 Liberty Nickel, I might worry more about the slight chance that "light" would hard them.

As I stated earlier, gases, moisture, and large temperature fluctuations are the biggest enemies of metals. I don't see how anyone could think "light" was on par with those elements. Light will fade paper money, stamps, documents, etc...but I see it having little effect on metal if the other elements are controlled (sorry Kasia, I don't buy the "water running over metal in light or dark" study...call me a skeptic!).

 

Shockwave, I forgot to say, Welcome to CoinTalk!

Maybe the answer you are looking for depends ultimately on your plan for the coins (future plans.)


Lucy

 

Kasia, do you have a copy of the actual paper? The preview basically says nothing. I'm curious (but not $10 curious) to see what the specified conditions were for the "fresh water stream," as well as the specific definitions of "dark" and exposure. If they're saying daytime/nighttime and using a run-off stream, that could be tidal influenced, in addition to the presence of light.

I know the preview says it was done under laboratory conditions, but it doesn't explain the stream. Are they using stream to mean a unidirectional flow, as opposed to a tidal current?

In any event, the preview merely indicates a loss of weight in the metals. It doesn't singularly indicate that the loss was due to the presence of UV light. In fact, it seems to indicate that UV light was a catalyst in a photoelectric reaction using a substrate created from the interactivity of the water and whatever oxidation coated the metals. While true that UV light (whether originating from sunlight or incandescent sources) may cause reactions in the coining metals, it seems the presence of water is the key. Without the water present to release the oxidized/excited metal from the surface, we can't say with any level of certainty that the metal doesn't merely return to a non-excited state upon removal of the UV source.

So, FWIW, did you actually pay the $10 to read the entire article?

As for the locality of the windowsill in question, I don't think the "SoCal" suburb is a good enough explanation. SoCal suburbia could indicate oceanfront property, inland empire, near desert locale, metro-LA, metro-SD or OC... lots of VERY different environmental conditions.

 

Wow. You are asking good questions. No I don't have the whole paper and I'm not 10 dollar curious. I am not sure that the run off conditions didn't have an impact like you state but at least it does in my mind limit what is supposedly measurable.also so cal is a huge area of differing conditions. I didn't even ask what direction the window faced.Tired right now. Will think on things.

 

Exactly. It's like some collectors act like Gollum in LOTR's, protecting their "precious".

I say display them proudly as well.

 

To be more specific, inland Ventura County. So I actually think I'm fairly well off in that regard. A pair of mountain ranges between me and the ocean, so coastal humidity isn't an issue. But still safely northwest of LA proper, so all the polution blows the other way.

 

I say take a good high res pic of the coins obv and rev. Display them and each week or month do the same. Document the conditions as well as location n e s or w facing, date, morning, afternoon, or all day sun, angle of sun over horizon when sun, and report back in, say, three years.That way you enjoy the display and we get some documented info on it.

 

I say... take common sense precautions and go ahead and display them. They're not the crown jewels. There's alot of good and
interesting info in this thread but some of it reminds me of this:

http://listoftheday.blogspot.com/2008/08/snl-classic-clip-of-day-anal-retentive.html

 

Ok, I've thought about it.....I don'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'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.
Probably you can't make a final judgement that is not questioned if you can'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.
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'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 "original" 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.
And Southern California does have a wide variety of climates and conditions. Where I'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 'raw' to the elements) you probably don't have that much factoring in. Say you encapsulate the coin in an air-tite or similar structure (which is not "air tight"). 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'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. 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.
I personally never intended to get this detailed about a subject that really for most coins doesn'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'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.
If these coins are not his "precious" then why worry about exactly how long or with what certitude damage will occur to a coin. Just enjoy the little buggers. It's just that his question wasn't should he display them, but would light affect coins. It's his choice whether to display them.

Bottom line, enjoy your coins....it's a hobby.