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I hope this is the best forum to ask this question on:

Where we live, mould is basically inevitable on anything that we put into storage for more than a few weeks, esp. on sensitive things like shoes. Air-tight containers with as little oxygen as possible (can't call it vacuum... :)) help for clean clothes but it's of course near impossible to get leather to the same level of through-and-through cleanness.

Which led me to wonder: what if instead of storing things under some approximation of vacuum, we store under regular atmospheric pressure but with the air replaced by an inert gas that won't allow anything aerobic to grow? You can get your tyres inflated with nitrogen, so even if I've never seen a workshop where they offer the service I assume that means that it doesn't require industrial or research lab working conditions.

I haven't yet found anything suggesting that there exist consumer grade storage solutions of a kind where you stuff things in a container (rigid or not), connect it to your nitrogen container and "flush out" the air from the box to replace it with the inert gas before sealing it.

Would such a system be conceivable, and would it indeed help with preservation?

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Air tight buckets and dry ice are used by some preppers to store food in oxygen free environments (as a bonus, it also kills any bugs hiding in the grain/beans). As long as you make sure that you don't end up with a crust of water ice on the outside you should be able to do the same to keep your items dry and mold free assuming they've been thoroughly cleaned before being put into storage.

What you do is to put a layer of dry ice in the bottom of the bucket, put whatever you want to store on top and then put the lid on almost but not quite tight enough to fully seal the bucket. Leaving a minimum opening is needed to prevent pressure building up from rupturing the bucket as the ice sublimates. After the initial partial closing you monitor the temperature of the bottom of the bucket, and seal the kid down when it's no longer extremely cold. If you're doing a number of containers at once you'll want to make sure your work space is well ventilated.

A 6 gallon storage bucket contains 1.5 cubic feet of volume, and you want enough CO2 to fill the volume about twice over to be confident you've displaced all the existing air inside. A pound of dry ice will produce 8.3 cubic feet of CO2. For something like shoes that have a lot of empty space it's probably best to assume the volume if what you're storing in the bucket is negligible for planning purposes, so you'd need about 5.8 ounces per bucket. At around a dollar/pound it's cheap enough that unless you're storing a lot of stuff at once you'll probably spend more on the gas going to get it than anything else.

Ultimately though, while more practical than Ed Beal's discussion about nitrogen filled warehouses, dehumidifying is still probably the more practical option.

My source for the above was: http://www.thefoodguys.com/dryice.html

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  • I had not considered dry ice (solid CO2, right?); I used nitrogen as an example because (AFAIK) it's not a greenhouse effect gas as CO2 is, but if dry ice is available easily that certainly makes it a good alternative over having to have a high-pressure container at home.
    – RJVB
    Jun 7 '20 at 17:12
  • The issue I see with dehumidifiers is 2-fold: they just displace the problem, and a truly dry atmosphere isn't good for leather products either.
    – RJVB
    Jun 7 '20 at 17:15
  • Yes, dry ice is solid CO2. Avoiding a pressurized container was why the instructions I posted had the container lid cracked open slightly to let the excess gas escape until the bottom started to warm (indicating it was all gone). Jun 7 '20 at 18:47
  • Your objections to a dehumidifier suggest you're not clear on how they work. They either have a collection point for water that is manually emptied or a hose to run to an existing drain, and remove water from the air, not just push it from one room to another. You're also able to adjust their operating point, and don't have to choose between swamp or desert. You can adjust it for a comfortable level that will neither encourage mold growth or desiccate everything. Jun 7 '20 at 18:48
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    I'm not talking about chemical moisture absorbents, but the appliance closely related to an air conditioner that will deswampify an room or your entire house. en.wikipedia.org/wiki/Dehumidifier Jun 7 '20 at 22:10
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I know some Fruit producers use a nitrogen atmosphere to keep the fruit in a dormant state then at thanksgiving they sell as fresh it has not been frozen. The warehouse/cooler is completely sealed and flooded with nitrogen gas then a small amount is constantly injected to keep air from creeping in as air is ~ 79% nitrogen and ~%20.7 Oxygen with other trace gasses, so yes it can be done

I think it may be less expensive to de humidify.

We keep several Dri-Z-air moisture collectors in our motorhome they keep the moisture low enough to prevent mold, if we do not have 2-3 of these full of the crystals and drain them every month or so we have mold growing in the motorhome within a few weeks of using it (we live in Oregon so mold is a fact of life here). I think there are other brands I just remember this one because we have used it for years and purchase the crystals in bulk when they are on sale.

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  • This hits on "modified atmosphere storage" I found were indeed about industrial-level food storage. I suppose we've all seen the mention "packaged under protective atmosphere" on food items, so this comes as no surprise, and it's what gave me the idea in the first place.
    – RJVB
    Jun 7 '20 at 17:10
  • The dehumidifying crystals used in dry-z-air the second part of my answer is probably the best method for a storage area. Our motorhome has leather seats and these are one of the things that mold / mildew first If we don’t keep the air circulating with the ac drying the air out. we have used this method for many years it is about the least expensive and works well even in Oregon.
    – Ed Beal
    Jun 7 '20 at 19:26
  • I think the key concept in your answer is circulating air. Clothes in a dresser will develop mould much less easily if air can circulate freely - presumably because airborn humidy is evacuated too that way. Sadly we don't have the luxury of having something like a dressing room where stored items can breath humidity (and temperature) controlled air. Instead, we must store our stuff in compact dressers, shoes often in plastic or paper bags, other-season clothes in containers. Much less easy to control the atmosphere there, except inside said containers.
    – RJVB
    Jun 7 '20 at 21:15
  • Our motor home is 33’ and we do not normally heat or cool it unless we need the extra bedrooms for family, just the dri-Z-Air one in front one in back and one in the bathroom in the winter. No circulation but we have run the AC to reduce the humidity after spending a week at the lake or coast.
    – Ed Beal
    Jun 8 '20 at 1:07

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