Dry Ice as Rust Protection

rhmc24rhmc24 Member Posts: 1,984 ✭✭✭✭✭
edited August 2007 in Ask the Experts
Does anyone have experience with this? In closed space like a safe, apiece of dry ice will turn to CO2 gas (sublimes?), a lot of CO2 from a small piece. It would largely replace the other gasses in the space, driving most of it out, including the oxygen that causes rust.

Probably of limited practical value for routine use but dry ice is easily available and for leaving one's safe unopened for a period of time the CO2 would produce a pretty much inert and oxygen free environment.

Is there anything harmful in CO2?

There used to be a powder Shell API 260, if memory is correct, called Vapor Phase Inhibitor that slowly turned to a gas and effectively prevented rust. It did cause heavy tarnish on brass.

Serious comments appreciated.


  • bpostbpost Member Posts: 31,144 ✭✭✭✭
    edited November -1
    too much Co2 will kill you fast! Why not just keep a protective coat of oil on the toys to prevent rust?
  • nmyersnmyers Member Posts: 16,368 ✭✭✭
    edited November -1
    CO2 is not especially dangerous, as long as you get enough oxygen. It's readily expelled from the body.

    CO (carbon monoxide), a byproduct of combustion, IS dangerous to breathe as it combines with hemoglobin in the blood as readily as oxygen.

    If you think of the kind of seal that is necessary to keep the CO2 from escaping from a carbonated beverage, you will understand how difficult it would be to keep it sealed inside a safe. If we were somehow able to seal a gunsafe, we would probably prefer nitrogen, an inert gas commonly used inside scopes.

  • glabrayglabray Member Posts: 679 ✭✭✭✭
    edited November -1
    You might make the situation you are trying to avoid even worse. Carbon dioxide dissolves in water to form a weak acid. If there is any moisture present (cold from the dry ice will cause moisture to condense out of the air) you might be storing your guns in an acidic environment.
  • allen griggsallen griggs Member Posts: 33,013 ✭✭✭
    edited November -1
    I know CO2 works in preserving food, ie you can have a five gallon bucket of corn, drop in some dry ice, and put the lid on loosely, let the dry ice evaporate, then seal it up. The CO2 displaces all the oxygen and weevils cannot live in that environment.
    As to whether it would prevent rust, I don't know, it is an intriguing idea.
    Also, you wouldn't need as good of a seal in the gun safe as in the coke bottle, because the coke is under pressure, but you don't need the safe to be pressurized.
    Now, there is plenty of oxygen in the CO2, but the oxygen is bonded to carbon atoms. In this configuration would oxygen cause rust?
  • PA ShootistPA Shootist Member Posts: 642 ✭✭
    edited November -1
    For many years I produced and sold Dry Ice (pure carbon dioxide in solid form at very low temperatures) as well as various industrial gases, such as nitrogen and argon. My thoughts are that while the evaporating Dry Ice block would possibly temporarily displace oygen-containing air in the safe as the gas expanded, it would lower the temperature in the safe substantially. The sublimation temperature (the process of evaporation froma solid without going through a liquid phase) unpressurized is close to -100 degrees Farenheit. And unless the safe were an air-tight seal (which it isn't, and if it were you couldn't drive out the air by displacement), room air will very soon return and the cold temperatures will condense any moisture from the air onto chilled gun metal. And as said before carbon dioxide will dissolve in water to form a mild acid solution. It might be far worse than doing nothing.
  • rhmc24rhmc24 Member Posts: 1,984 ✭✭✭✭✭
    edited November -1
    Some good thoughts here as well as otherwise. I think I will do a test by putting some dry ice and a piece of bare iron in a box, close it up and look at it in a month or so. I will post my findings when/if I get any. Thanks.

    Any more contributions???
  • He DogHe Dog Member Posts: 48,610 ✭✭✭
    edited November -1
    Sorry, that is a decent idea, but not a well designed experiment. You would need to use blued steel and not bare iron. Bare iron will oxidize in any event and will not be a valid test for whether blued steel will oxidize under those conditions.
  • work4gunswork4guns Member Posts: 31 ✭✭
    edited November -1
    I've done the food storage with the dry ice before. Many people do this. I'm not sure about guns.

    I think the tried and true method is to just keep your stored guns in a thick coat of oil and bagged up.
  • rhmc24rhmc24 Member Posts: 1,984 ✭✭✭✭✭
    edited November -1
    I should have said I will use steel rather than iron in my experiment. Rather than get the cart before the horse here, it is true that bare (whatever) is more prone to rust than the same when blued. I have had experience with bare steel, aircraft parts, in keeping them free from rust in all sorts of climate conditions. The VPI (vapor phase inhibitor) I mentioned did a good job. I will try to put vulnerable bare steel protected by CO2 to the test. Stay tuned.
  • givettegivette Member Posts: 10,886
    edited November -1
    Go down to your local gunsmith. Ask him for his "throwout" parts. Put them in there instead.

    ...then you'll be working experimenting with the correct metallurgy, bluing, etc.

    Best, Joe
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