What is the "ideal storage environment" for raw coins or slabbed whether attainable or not? 1 1

[Henri Charriere]

The Qumran Caves provided an ideal storage for the Dead Sea Scrolls; the bottom of the Black Sea, devoid of light and air, but cold, proved to be an ideal resting place for sunken wooden vessels.

What is your understanding as to what would constitute the ideal storage environment for raw coins and/or slabs, if you feel it matters.  Consider temperature, gases, humidity, and exposure to extremes in temperature as well proximity to factors you feel are important but rarely mentioned.

[RWB]

Coins and their packaging or holders might require different "ideal" storage conditions. It's likely to vary with protection vs prevention.

[VKurtB]

There is no one ideal storage method. Different metals have different needs. Of the “popular” metals for coinage, gold is the most forgiving. But it has its own “kryptonite” which is chlorine. Silver’s “kryptonite” is sulfur. Copper has several natural enemies, of which oxygen, sulfur, and moisture are kings, This is why great copper coins are seldom found in Mylar holders. Too much moisture retention.

Edited January 14 by VKurtB

[powermad5000]

This is a good question and I have not seen any source to give any specific (scientific) answer. I have often wondered when seeing early 1800 Large and Half Cent coppers that are still RB or the few in RD, and also early Indian Head cents still bright and RD, how and where they were stored for so long without modern accoutrements after they were struck. Seeing some of these imho to find that out would be a good clue towards the answer.  Were they stored in a regular paper envelope? Were they stored open and raw in just a drawer or wooden box? What about the temperature and humidity of the room? Would the location in the country have any advantage or disadvantage in regards to average annual temperature and humidity?

Just my opinion, but I think a temperature that is somewhat stable is important, but not sure what the ideal temperature would be. I think wild temperature swings would be bad for the place where the coins are stored.

I think one of the most important factors would be relative humidity. I say this because I had an experience on one of the jobs I was on many years ago and it stuck with me. I always had my tool bags in gang boxes inside buildings with controlled temperatures and humidity. There was one job (and some of my tools are still affected by this event) where the building was not yet complete, there were still gaps in the some of the walls so it was not a controlled environment. The roof was on and sealed so there was no leaking or water getting into the gang box but it was like storing your tools outside (not even in a garage unless you left the door open for months which nobody really does). There was one night during the summer where the temperatures spiked overnight and the relative humidity was 100% but the air itself felt like it might as well be jungle and that nasty air felt like the humidity was 125% even at midnight. The air was soupy, thick, and you could go outside after dark, step out of the AC of the house, and literally sweat horribly just standing still. When we came in to work in the morning, and opened the gang box, I pulled my tools out and started to select the ones I needed for the morning. I was a little shocked to find ALL of my tools had developed surface rust overnight from that nasty air. Every single tool of mine that was not chromed had turned brown. Everyone's tools including the shop's tools all were the same. I had to take my whole bag home that night and glove up with a rag wetted with WD40 and wipe every tool. Some on the bottom of the bag cleaned up ok, but some on the top of the bag never cleaned up and still have rust on them to this day. This is why I think the relative humidity level of where the coins are stored is the most important factor. I don't know what an acceptable amount to not exceed would be but I would say that the less would be the better. I know silver if left out for long enough exposed to open air (5 or 10 years) with 25-30% humidity that those coins with less than perfect surfaces will tone (one of my circulated Morgan dollars did this). I would be interested to know if anyone on here has done any scientific testing of humidity and moisture on different metals.

[RWB]

For bare coins, tarnish and surfaces are best controlled with low humidity, low oxygen exposure, no added contaminants, and moderate temperature --- 20-degrees C being the standard. This is close to powermad5000's tool gangbox example. Ideal might be positive pressure helium/argon atmosphere with 0% humidity, low light and no exposure to packaging out-gases.

Geographically, look for areas away from moisture, especially the ocean or large body of water, or humid conditions; areas away from coal, natural gas or processing facilities (sulfur), chemical manufacturing, and so forth.

[J P M]

I live on a Island. High humidity and sulfur marsh everywhere. Some days it smells like egg salad everywhere. Ya my coins will most likely tone more than others. I do what I can to help them out but there is no guarantee. 

[zadok]

On 1/15/2024 at 1:22 PM, J P M said:

I live on a Island. High humidity and sulfur marsh everywhere. Some days it smells like egg salad everywhere. Ya my coins will most likely tone more than others. I do what I can to help them out but there is no guarantee. 

...hmmm, i always thought that smell there at buzzards bay was from the fish who knew eggs too n then there were the skirted hustlers at the local pool hall there but i digress...im thinking best place to store coins is coppers to the red states n silver to the blue states n gold ill store in boxes upstairs under the guest bed c.o.d. shipments accepted....

[RWB]

Put silica gel packets and sulfur absorbent with your coins in a closed box. Change both absorbents regularly.

[VKurtB]

And avoid close proximity to dairy herds. 

[powermad5000]

On 1/15/2024 at 5:31 PM, RWB said:

Put silica gel packets and sulfur absorbent with your coins in a closed box. Change both absorbents regularly.

What would be considered a "regular" time period? How long do silica gel packets last? Do the large size packets last longer? Can the ones inked with "Made in China" be trusted? Sorry, I like specific information.

[RWB]

The usable life of silica gel (aka, silica xerogel) depends on the humidity and air circulation. The best commercial products have an indicator added so the material turns blue when it's saturated. You'll have to test for longevity. In a humid place, such as the Gulf Coast, you might have to replace every month. I am not familiar with any specific brand -- you'll have to read the labels. Hardware stores and some coin shops carry silica gel.

You can regenerate it by gently heating to about 120F for a couple of hours.

Edited January 16 by RWB

[VKurtB]

https://www.wizardcoinsupply.com/products/silica-gel-desiccant/
 

[RWB]

PS: Humidity is nasty stuff for coins. Suggest you rotate packets so your coins are not left unprotected for even a few hours. (At the old New Orleans Mint rust prevention required constant attention. If you are looking for coins made from "rusted dies," NO is the place to look.)

[Fenntucky Mike]

On 1/16/2024 at 2:09 AM, powermad5000 said:

What would be considered a "regular" time period? How long do silica gel packets last? Do the large size packets last longer? Can the ones inked with "Made in China" be trusted? Sorry, I like specific information.

I'm in the same region as you and I change them around once a year, usually only a few of the pellets have turned color by that time, or none, I keep my coins in closed cases for the most part with packet/s in each case. I'm also in a home with air conditionin', which is not always the case around here, and have a woodstove going in winter which dries the place out like you wouldn't believe. Just keep an eye on them as everyone's at home conditions are different. I like the 2g packets myself but it'll depend on your setup. You can pick some up on amazon or wizard and I've never had an issue with any of the brands I've bought, 

 

[VKurtB]

On 1/16/2024 at 11:48 AM, RWB said:

PS: Humidity is nasty stuff for coins. Suggest you rotate packets so your coins are not left unprotected for even a few hours. (At the old New Orleans Mint rust prevention required constant attention. If you are looking for coins made from "rusted dies," NO is the place to look.)

I myself rusted visibly when I stopped in New Orleans after the 2016 Anaheim ANA show. Amtrak Sunset Limited. I grew a little mold, too. 

Edited January 17 by VKurtB

[numisport]

On 1/16/2024 at 12:28 PM, RWB said:

The usable life of silica gel (aka, silica xerogel) depends on the humidity and air circulation. The best commercial products have an indicator added so the material turns blue when it's saturated. You'll have to test for longevity. In a humid place, such as the Gulf Coast, you might have to replace every month. I am not familiar with any specific brand -- you'll have to read the labels. Hardware stores and some coin shops carry silica gel.

You can regenerate it by gently heating to about 120F for a couple of hours.

Agree but regeneration of my boxed silica seems to work well in the oven. Problem is most ovens (even with newer solid state controls) have minimum heat of 170. Like you stated the object is to slowely bring the temp up given enough time to thoroughly dry out the silica media. Cardboard cartons that store the silica seem to take that 170 fegrees just fine.

[RWB]

Use a standard oven thermometer and when the temp is a little over120F, turn the oven off and put in your silica gel. (No need to baste, rotate, turn, braise, or broil.)

[VKurtB]

On 1/16/2024 at 8:01 PM, RWB said:

Use a standard oven thermometer and when the temp is a little over120F, turn the oven off and put in your silica gel. (No need to baste, rotate, turn, braise, or broil.)

In Alabama, the good ol’ boys fry them, in the driveway. Oh wait, that’s the late November thing.