*Custom Sized Mylar Pouches*
A Gallon is Just TOO Big
By: Osage
15 October 2003

Mylar pouches are a wonderful method of food storage. No, they’re not the best solution for all applications, but they do a lot of things very well. Mylar pouches are quite vulnerable to rodent attack, so they must be stored in a rodent-proof outer case or in a rodent-free environment. I still prefer to store bulk grains in 5-gal buckets, but some of them are in Mylar pouches with oxygen absorber packs inside the buckets. I store many other items in #10 cans or large bags in metal trash cans. On the other hand, one 200+ lb (and the amount of plus is between me and my First Sergeant) Cannery Manager I knew was fond of placing a newly sealed pouch of wheat on the floor, jumping into the air, and landing on it with both feet. I never had one pop or even develop a pinhole. That’s tough! Mylar pouches have a definite place in my scheme of storing food and other items against hard times.


One major problem with Mylar pouches is that they come in sizes which suppliers find sell the best. The smallest I can routinely find near my home in the SE US is the 1-gal pouches available at LDS (aka ‘Mormon’) Family Canneries. Now a 1-gal pouch is great for rice and beans. But it’s a real hassle ™ for egg powder or spices. One gallon is way too much cinnamon to open at one time, even as much as I love it in my hot chocolate. I began playing with fractional sizes of the LDS pouches to determine how much some of them would hold.


First a quick note on three-dimensional geometry. The pouches are two flat pieces of Mylar sealed along three edges. They are filled by pulling open the top, dumping stuff in, and pulling the open edge flat again to heat seal it. A 1-gal pouch starts out roughly 11 ¾ " X 13 ½ " when flat. Since Mylar doesn’t stretch to any significant degree, the edges have to move closer together while the sides move apart to produce a three-dimensional pouch. Smaller pouches have less ability to do this, so half of a 1-gal pouch will only hold about 6 cups, not the half-gallon (aka 8 cups) you might expect. Another geometric restriction is that if the pouch is significantly other than square (a rectangle that’s more than a bit longer than it is wide), the open side really needs to be one of the short sides. Otherwise you waste a lot of capacity. This really only applies to the half, third, and sixth size pouches, since the full, quarter, and ninth sizes are close enough to square. (See below)


Listed below are the sizes and capacities of several fractional pieces of a standard LDS Mylar pouch:

FractionCapacityApprox Size (flat)
Full1 gallon (16 cups)11 ¾ " X 13 ½ "
Half 6 cups5 ¾ " X 13 ½ "
Third 2 cups (32 T)3 ¾ " X 13 ½ "
Quarter1 ½ cups (24 T)5 ¾ " X 6 ¾ "
Sixth 9 T3 ¾ " X 6 ¾ "
Ninth5 T3 ¾ " X 4 ½ "


If you’re not familiar with sealing Mylar pouches, a word is in order. I’m fond of the machines at the LDS canneries. They’re industrial strength items with the settings specifically set up for the Mylar pouches they use. When I can’t make a trip to the cannery I have used a home clothes iron and a smooth board, and have had some luck with commercially produced bag sealers made for home use (mine is an old Dazey). Whatever you use, practice with it a bit on empty pouches. A Mylar pouch full of product is an unwieldy critter and not the thing to learn on. You’ll need to play with the heat setting, the length of time the heat is applied (called dwell time), and the amount of cooling time (if your machine has that option). If the machine doesn’t do the cool down while it is still clamped, be careful when removing the pouch from the sealer. The Mylar is still hot and is quite prone to pull apart until it cools (in a few seconds).


OK, in the words of an old joke: Now that I have it what do I do with it? Well, I believe the one-ninth size, at 5 tablespoons, is just too small for storing any food item of interest to me. I might consider it for pre-packaged spice mixes for a marinade or something on a camping trip, but for long-term storage of even spices it seems too small. The one-sixth and one-quarter sizes seem fine for spices, egg powder, cheese powder, and the like. The one-quarter and one-third seem about right for soup mix or similar pre-packaged BOB or cache items, or perhaps something like barley, dried onions, dried carrots, dried peppers, or the like. I’m also fond of storing a bit of brain candy (literally) like peppermints, other hard candies, or Tootsie Rolls (milk chocolate can go stale). The one-quarter to one-half sizes seem about right for special treat items like this.


Now for non-food items the list of possibilities is limited only by the fertility of your imagination (and this board has some very ‘fertile’ minds). Some of my ideas verge on the problematic for liability, so I won’t record them for posterity. Use your imagination, but be careful of heat around some substances. Mylar is waterproof and quite tough, so it can handle quite a bit of mistreatment. I am unaware of its resistance to common chemicals. Test it thoroughly for any off-the-wall applications you may consider.

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