Displaying Coins and Sunlight

but where am i supposed to get a car's dashboard?

 

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Having read everything that people have said here, I feel like the usefulness of proper encapsulation is being understated.

Allow me to back-story that a little.

I am 30 years old, and the majority of my collection are coins that my parents bought for me as a half-hearted hobby back when I was a kid. So things from the early 90's, etc. The coins were not stored properly for a majority of that time. For the most part, in a shoe box that was located in a part of the house that was not climate controlled.

Fast forward to a few months ago when I unboxed them all and took a renewed interest in the collection. Among other things, there are a total of maybe five 1oz Silver Eagles. Two of these, from '92 and '93, look to have been originally from a roll, and were slapped into cheap hinged plastic cases by some dealer years ago. Now all these years later, there is visible darkening and tarnish around the edges of these two coins. By contrast, the other Eagles from the same time period, stored in the same box in the same location, look absolutely beatiful. The only difference that I can see is that these were stored in their proper US Mint capsules.

Since everything I am now planning to display is likewise encapsulated, it makes me think i have that much less to worry about.

 

Doug, you are right that such items fade. But curtains, carpets, rugs, furniture, paper, stamps, etc. all fade because of degradation of either organic compounds (proteins) or because of degradation of polymers (fibers and plastics). This degradation is NOT limited to light from the UV spectrum (< 400nm), and these items are NOT made of metal. Have your pots and pans suffered "fading" because of UV light? I doubt it.

As for your other comment, MOST UV light IS blocked by ordinary pane glass. Not all, but more than 90% of radiation less than 300nm is blocked. More of the UV spectrum from 300-400nm can pass. If you want an example of this in practice, "transition lens" glasses will NOT work behind any standard soda-lime glass (window glass). These glasses "transition" because of UV light, and work in direct sunlight but not in cars (for example). As another example, test tubes used in spectrophotometry specifically do NOT use standard glass (window soda-lime glass) because it blocks UV light. They use a more expensive quartz-silica glass that is transparent to UV light. So despite your draconian and dogmatic statement of my being "100% wrong", I beg to differ.

 

Several studies of factors determining the total amount of UV radiation at a geographical location have indicated that altitude and closeness to the equator are the most consistent factors. The largest study says the effect of altitude varies from 9% to 24% per 1000 ft. So much more UV at Flagstaff @ 7000ft compared to San Diego @less than a 1000. That said, I feel that UV effects on metallic silver would be zero if the metal was in a vacuum and the UV was at a maximum environmental level on earth. Studies on nanoparticle size of silver may have quantum type reactions, but a silver coin is not nanosized.

Most older experiment using UV and water did not eliminate such factors as the amount of ozone. UV can break down ozone and release reactive oxygen singlet that then can react with metallic silver.

I think for silver objects it is still environmental factors such as ozone, H2S, etc., than UV levels that determine any tarnishing. So if you can't change the environmental factors , use the tightest sealed holder. IMO.

Jim

 

Because sunlight bleaches fabric.

 

If you like your coins the way they are, sun (actually, more correctly, a change in temperature) is bad. I do not believe that UV affects metals, per-se.

I would keep them far, far away from any windows, if it were me.

 

Sunlight is made of more than UV radiation. For example, have you heard of the VISIBLE light spectrum?? The degradation of things made of cloth (proteins) or polymers (plastics/polyester, most carpets, curtains, etc) can occur because eletromagnetic radiation causes their corrosion. My point was that just because a curtain made of basically an extruded plastic fades, this has nothing to do with the possible effects of light on metals. You're comparing apples to oranges.

At any rate, we fundamentally agree that other elements are far more important, and thus it's still just a personal preference of the OP. As a disclosure, I don't store my coins in plain sight anywhere for the mere fact that I don't care for that many people to know that I collect coins. It's one things to share the hobby with a YN or a close friend; it's quite another thing to broadcast to the world that you likely have "more where that came from".

 

Needs to be quantified. how much loss are we talking about? Micrograms, nanograms less? How much was lost just from the flow of water over the samples? If there hadn't been a flow of water to carry those atoms of metal that the occasional UV photon brokeloose away would there have been any metal loss? What was the intensity of the UV radiation? Without a lot more information this is meaningless.

Oh and put a layer of glass in front of the coins and you cut the UV intensity significantly.

This is true, but the heating effect from indirect light is probably fairly insignificant. The heating effect from you standing there looking at them would probably be greater. A much greater heating effect would come from whatever direct sunlight falling on other items is heating them and raising the temperature in the room. This is offset by the room's temperature controls.

Intense light can have an effect on metals, typically by knocking off electrons and maybe once in a great while even displacing an atom. An electrically unbalanced atom might be more likely to react with an atom from the atmosphere. I don't think you would any problem with indirect lighting though.

Indirect lighting, temperature and humidity controlled, coins encapsulated, glass fronted display case, I'd say decades if not centuries. Probably more at risk from the long term degradation of the plastic, paper, and inks inside the holder (Depending on the holder generation) If the coin is stable in the holder then centuries would not surprise me.

 

This request will never have a response. I don't believe it is something the TPG's can detect or even attribute it to the cause. It's a theoretical issue. It's like saying my presence in the universe is felt by all the mass within it. You can't disprove it, but it is meaningless in everyday life if it does.