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Thread: Dirt Cheap Ammo Can and Safe Dryer

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    Dirt Cheap Ammo Can and Safe Dryer

    We all know, or at least suspect, that for the long term it is good to store ammo and primers in a low humidity (dry) area. I have been trying out a cheap ammo can dryer for some time. It is similar, if not identical, to the silica gel stuff you see sold in many places as a safe "dehumidifier" for $8 to $79 per pound. You may also hear it called desiccant. (It is also the same material as in those small paper packets included in the boxes with new electronics, shoes, and some medicines. You know, the ones that say "Do not eat".) The big difference is that the stuff I have been using is sold as Mimi Litter cat litter at Walmart and costs about $4 for four pounds. Some of the more expensive stuff sold elsewhere does have a moisture indicator additive that changes color to show when the batch needs to be reconditioned (baked).

    I found that some bags of the Mimi Litter were mostly white and some were mostly blue in color. I bought one of each at different times. At first, I thought that the blue color in both bags might be some kind of moisture indicator but I now think the blue color is just dye.

    Two Colors Available:


    I had been taking the drying ability of the litter on faith until I started my non-scientific test back in early September of 2013. I wanted to see how well the litter really worked for lowering the humidity in a typical ammo box. Since one of the bags had been sitting in my garage for over a year, I started by putting samples from the two bags on a cookie sheet and baked them in an oven at about 230F for 4 hours. From what I have read, that is one recommended way to rejuvenate silica gel after it absorbs all the moisture it can hold. Both samples looked exactly the same before and after the baking. I think that indicates that the color difference between bags is meaningless and there is no moisture indicator included. So, I just mixed the two samples together and put them in a sealed glass pint jar until I needed it.

    After Baking:


    I wanted some cheap porous container for the litter that I could put in small spaces and that would expose a lot of surface area. I also did not want the liter granules spilling all over the place. I settled on plain old coffee filters folded in half and stapled around the edges to make a pouch. I left one end loose until I could put in about 5 tablespoons of litter through a funnel then stapled the end shut. I could have added a lot more litter and it would not have overfilled the pouch. I stopped there just because that was near the limit of the reloading scale I wanted to use to accurately weigh it.

    Coffee Filter:


    The original weight of the pouch and litter on September 3, 2013 was 1.28 ounces. I forgot to record the initial room humidity but I think it was above 70% which is typical for East Tennessee. I placed the pouch, a humidity meter, and several bricks of that rare stuff called CCI 22LR ammo in a 50 cal ammo can. The can was about 3/4 full. On Sept. 26, I opened the can and weighed the pouch again. The weight had gone up to 1.328 ounces, indicating that it had absorbed some moisture. As I recall, the humidity meter read in the low 60% range.

    I kind of forgot about the test for awhile and did not check that box again until June 30, over 9 months later. When I opened the box, the humidity was down to 51%. (I have read that 40% RH is about the best that can ever be expected using silica gel.) The reading went up to 53% within seconds, actually before I could quickly turn on the camera and take the photo below. Fortunately, the 51% is recorded as the low on the meter. I weighed the pouch again and was surprised that it weighed almost exactly the same as the last check. I guess it absorbed all it could under the conditions but it got the job done. (Technically, silica gel can absorb water equal to about 35% of its original dry weight so it could have weighed as much as 1.6+ ounces before it would be "full" and need drying again.) I put the pouch back in the ammo can and closed it then placed the humidity meter on the workbench. After a little while, the meter showed the humidity in the room at 77%. That is a 25%+ difference or reduction in humidity in the ammo can. It is also far better than I have ever been able to get in my safe using one of those hot-rod type heaters made specifically for humidity control in safes.

    Relative Humidity After About Nine Months


    Like I said, this was not a scientific test, but I am satisfied with the results from the Mimi Litter and will be making more of the pouches for other ammo boxes. If I needed that many, one bag of litter could make about 50 pouches like the one I tested. And it is cheap, cheap, cheap.

    I also may make several pouches to scatter around in my safe but I will probably make them larger. Perhaps by stapling two filters together back to back and putting in a lot more litter. From what I have read, it would probably take about 16 ounces total of the silica gel for a typical safe. I can do without the color change ingredient in the expensive stuff. Every few months I can just empty it all out on a cookie sheet and bake it for a few hours to rejuvenate it. I might even try heating it while still in the filters as the baking temperature is not hot enough to ignite paper. Or, I could just throw it all away and start over with fresh litter and filters. If I seldom open the cans or safe, the litter obviously will last longer since no new moist air would be getting inside the boxes.


    (By the way, the Mimi stuff also works pretty good as cat litter.)
    "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." -- The United States Constitution, Amendment 2, Ratified Dec. 15, 1791

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    Why do you let your house have 77% humidity? I've got a 250 pint dehumidifier and the highest it's ever gotten was 60% after taking a hot shower. The lowest humidity I've seen was 37%. I have severe allergies anything over 50% humidity is dust mite heaven.

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    Last edited by 45acp; 07-02-2014 at 11:06 AM. Reason: removed quote of post #1 (too long)

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    Quote Originally Posted by tdoccrossvilletn View Post
    Why do you let your house have 77% humidity? I've got a 250 pint dehumidifier and the highest it's ever gotten was 60% after taking a hot shower. The lowest humidity I've seen was 37%. I have severe allergies anything over 50% humidity is dust mite heaven.

    Sent from my mind using ninja telepathy.
    It is in a unheated, non-conditioned basement with a garage door that gets opened regularly. Typical storage area...which is why I need a dehumidifier for my ammo boxes.
    "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." -- The United States Constitution, Amendment 2, Ratified Dec. 15, 1791

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    Quote Originally Posted by 45acp View Post
    It is in a unheated, non-conditioned basement with a garage door that gets opened regularly. Typical storage area...which is why I need a dehumidifier for my ammo boxes.
    Ahhh

    Sent from my mind using ninja telepathy.

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