Moisture Control For Long Term Storage.

Here in Phoenix, we don't really have that much to worry about moisture. we live in an oven year round.

Coins alone should be able take the dry heat. However, I would worry about storage—albums, holders, etc. Their materials may break down in really high heat and cause damage. So, I would be running the AC there, even if it has to be on 85°F just to keep from going broke.

Yes. Attics and basements are really bad places unless there is some sort of climate control.

They're mostly all Made In China these days, so quality can be random, even for 2x2s sold under the same "brand", as they may have been made at different times and places.


If you're going to be staple-avoidant, you may as well spend the extra money and buy self-adhesive flips. Anything adhesive is a potential outgasser as it ages; as with the flips themselves, it's a matter of trial and error.


Get yourself some self-indicating silica gel. The typical formula contains cobalt chloride, which is blue when dry and pink when wet. The indicating crystals not only tell you when they're wet (and thus need refreshing), but also help you in the refreshing stage: put pink silica gel in a cool oven (less than boiling) until the crystals all turn blue again. Raw silica gel is mostly harmless but cobalt chloride is toxic, so don't eat them.

Neither silica gel, nor cobalt chloride, will outgas. In my experimentation, indicating silica gel is harmless to coins unless the pieces of gel are in direct physical contact with the coins. Avoid doing that, and you should be golden.


The boxes cannot be made of the same acrylic as the slabs, because putting two similar plastics together is always a bad idea, as they tend to stick together with time and/or pressure - this is why plastic bottle caps are always made from a dissimilar plastic to the bottle itself. But I'm sure the slab-box plastic has undergone the same rigorous testing to be coin-safe as the slabs themselves.

This is a very educational thread. Here is what I have gathered so far:

Coins should be stored in Mylar and cardboard flips. Due to everything being made in China these days, brand name is not necessarily a guarantee of top notch quality. The self-adhesive flips could possibly outgas, and my painter's tape is maybe not a great idea, so I should probably just get comfortable with stapling flips the proper way.

It's fine to store 2x2 flips in plastic boxes. Same with slabs. Nothing but the flips and slabs go in the boxes.

The 2x2 storage boxes should go into a Tupperware container.

Desiccant packs should be placed in the Tupperware. They shouldn't be near the coins themselves. You can buy self-indicating packs that turn from blue to pink when they absorb moisture. These can be gently dried in the oven and reused.

The Tupperware container should be stored somewhere dark, cool, and dry. The desiccant packs should be checked every few months.

If you have raw coins, you might consider CAPS holders. https://www.capsalbums.com

The 2x2s work well for most coins, if you do three things. First, use needle nose pliers to crimp down the staples. Second, pack them tightly in the 2x2 boxes to prevent the coins from moving. Third, store them in a dry place. Either use large dessicant containers or a dehumidifier to remove moisture from the area. If you use the dessicant containers, remember to replace them as recommended. Circulated coins that I put in the cardboard 2x2s in the 1960s and 1970s were still fine when I liquidated my inventory and collection over the last few years. BU coins I put in Capital Plastics holders back then were exactly the same all these years later. I'd be cautious in using any kind of tape to seal the 2x2s because of the chemicals in the tape, and I'd avoid all of the paper 2x2 flips.

Coins I put in the older albums (all mine were Wayte Raymond / National Coin albums) were in great shape, but had acquired beautiful light toning over the years. My Buffalo nickel collection toned lightly with the classic gold tint that those particular albums produce. The silver coins toned lightly near the rims. The bronze coins didn't change at all. Gold coins, naturally, did fine.

Coin tubes work very well over longer periods. Long story here, but I'll give the short version. Way back in the day, Grover Criswell talked me into buying prooflike Morgan dollars, when everybody hated them. (People thought they looked "weird" and wanted what we later called the blast white coins.) I took his advice, and went a *little* overboard in buying them. I stored them in tubes, with a cotton ball on top and on the bottom. I've been liquidating that part of the inventory a couple hundred a year for the last few years, and will finish that task in the next year or so. ALL of the coins were and are exactly how they looked when I put them in the tubes 45-55 years ago.

These coins were stored in a large safe, with a dessicant tub that I swapped out every 6 months. My safe was stored at a climate-controlled property title office inside their huge records safe. That office was located in a dry adjoining state.

Yes, it's bone dry here. But other environmental factors like annual wildfire smoke can affect the coins. Flash floods and tornadoes aren't recommended, either.

I found that these storage methods worked well.