Food Storage Part II: Unraveling the Mystique of Mylar Bags

Food Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor SurvivalToday I would like to help unravel the mystique of the Mylar bag.  As with the ubiquitous oxygen absorber, the mention of Mylar bags brings up as many questions as there are answers.  We have all heard that the best way to store dry goods for long term storage is in a Mylar bag but what exactly is a Mylar bag and, more specifically, how are they used?

What is a Mylar bag?

First and foremost, the term “Mylar” is actually one of many trade names for a polyester film called BoPet.  For the technically inclined and the curious, that stands for “Biaxially-oriented polyethylene terephthalate”.  This film was developed by DuPont in the 1950’s and was  first used by NASA.

Since then, many uses for Mylar have been embraced due to its high tensile strength and its moisture, light, gas and aroma barrier properties.  Mylar is a also good insulator against electrical disturbances.

For all of these reasons and more, Mylar bags are considered a gold standard when it comes to long term food storage.

Okay.  I get it.  What size and thickness do I need?

The two most commonly used sizes for storing food products are the one gallon size (about 10” x 14”) and the five gallon size (about 20” x 30”).

The gallon sized bags are ideal for grains, dried powered foods, spices, hard candy, salts, and other baking ingredients. In addition the gallon bags are useful for protecting valuables including ammo, and medical supplies.  When shopping for gallon sized bags, you should look for a thickness of 3.5 to 4 mil.

The large, 5 gallon sized bag is typically used to line a 5 or 6 gallon plastic bucket.  The bag is filled with product then sealed before closing the bucket up with a lid.  The combination of a Mylar bag inside a plastic bucket makes an unbeatable barrier against the woes and ravages of time, moisture, light and most important, rodents.  The bag alone will not keep out the rodents!  For that you will need a bucket.

Because of the weight of its contents, the thickness of a 5 gallon Mylar bag should be 4.5 mil or more.  And, just so you know, the thicker the bag, the tighter the weave of the polyester – that is what gives it its strength.  As a matter of fact, you will find bags that are 7 mil and even thicker but for most uses, 3.5 mil to 5 mil will work just fine.

Tips for Sealing a Mylar bag

Sealing a Mylar bag can be a challenge but with a little practice, you will find the process simple and efficient.  You can use a clothes iron alone, or a with a FoodSaver and some extra tubing.  But, for an easier and less costly solution, try using use a hair straightening ironFood Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival which will only set you back $20 or so.

Here are some other tips:

  • Do not overfill the bag.  Remember that your oxygen absorber will suck out the oxygen, leaving only nitrogen in the extra space.
  • Only seal the top inch of your bag.  If you need to cut open the bag to remove product, you have the space to seal the bag back up again.  Just don’t forget to add a fresh oxygen absorber.
  • If you are sealing up a powdery substance such as flour, be sure to wipe the inside edges first so that any residual dust is removed.  This will insure a good seal.
  • Check your newly sealed bags a few days after sealing.  They should be noticeably compressed.  If not, there is a likelihood that the seal was not good or a hole was poked in the Mylar.  Give it another week and if is still is not compressed, cut it open and start over.
  • When sealing pasta or noodles, feel free to seal them in their original packaging.  Cut a little hole in the package first, so that the oxygen absorber can do its job in removing every last bit of oxygen, even from the store packaging.
  • Remember, heat is your enemy regardless of the packaging.  Store you packaged products below 85 degrees and preferably much lower than that.

What about Vacuum Sealed Bags?

Vacuum seal bags, such as those for the FoodSaver are a wonderful convenience and easy to use. But alas, they do not have the thickness nor the strength of Mylar bags and the may start to leak after 3 or 4 years. That said, they are still a great alternative for your short-term and mid-term storage items, especially if you are diligent about rotating foods and using them for your normal meal preparation activities. Just be sure to include an oxygen absorber if you plan to store your vacuum sealed bags for over a year.

Need more information?  Let’s Do Show and Tell!

The following video was put together by a fellow prepper at the Big Sky Tactical YouTube Channel.  Take a look and if you are so inclined, go to YouTube and subscribe to some of Fletch’s other preparedness related videos.  He’s a great guy – just be sure to let him know that SurvivalWoman at Backdoor Survival sent you!  Here is a link:  Tips for Long Term Food Storage.

Also check out the Backdoor Survival article,  Hands on with Mylar Bags, Beans and the FoodSaver as well as Food Storage Part I – A Primer on Oxygen Absorbers.

Stay tuned for the next installment:  Food Storage Part III – Buckets and Gamma Seals.

Enjoy your next adventure through common sense and thoughtful preparation!


Backdoor Survival Tip of the Day:  Live a long way away from a warehouse store or a large supermarket?  If you know your prices, take a look at the grocery items available at Amazon GroceryFood Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival .  I was shocked to find my favorite bottled salad dressing for about 1/3 the price of our local store which never puts it on sale.  I mention this here because “who’d a thunk it?”  Also, you just might find the price cheaper than Costco.  Check out the price of honeyFood Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival, for example.

From the Bargain Bin: Food Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor SurvivalCurrent SurvivalWoman picks.

Mylar bags & Oxygen Absorbers:  The current price for 20 gallon sized bags plus 20 oxygen absorbers is $14.46.  I have seen the price of these come down over the past few months – this is about $5.00 less than I paid.

Remington Hair Straightening Flat Iron:  Perfect for sealing those Mylar bags.  This Food Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survivalone is less than $17 with free shipping. For this purpose, there is simply no reason to spend more than that.

Lodge Logic 4-Quart Cast-Iron Camp Dutch OvenFood Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival:  Love it love it love it.  This is the perfect size for all types of things:  baked beans, stews, and my favorite, peach cobbler.  Watch for a review soon!  Don’t forget the Lodge Set of 2 Pan Scrapers, a must have for cleaning those food bits from your cast iron cookware.

Sabre Family Home and Property Protection Pepper Spray (13.0-Ounce)Food Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival: From the company that makes bear defense sprays, this pepper spray has a range of 30 feet and can be mounted right near the door.

550lb. Type III Paracord 100′ BlackFood Storage Part II: Unraveling the Mystique of Mylar Bags   Backdoor Survival: I wish I had known about Paracord years ago. With a recent price reduction to less than $8.00, there is no reason not to have a few hundred feet around your home, in your car, and in your bug out bag.


Food Storage Part II: Unraveling the Mystique of Mylar Bags — 13 Comments

  1. Great article Gaye, and thanks for the shout-out for my You Tube channel . I see I have reading to do here. ;-)

    For those that like watching videos as well, please check out my channel. I cover the 5 P’s. Prepping, Protection (Personal & Property), Planning, Product Reviews, Patriotism and some Politics here and there. If you like what you see please subscribe so that you’ll see the new video’s as they come out.

    Thanks again Gaye!

  2. I’ve used a clothes iron to seal my bags for years and over that time I have seemed to perfect the craft. My advice would be to allow the bags to set a day or so after sealing and before placing in a bucket to ensure the seal did in fact take. After inspecting some of my earliest attempts I would that, while the bag certainly looked sealed, there was still a pinhole I missed. The easiest way to check is to lightly squeeze the bag and listen for air movement, although sometimes this can be difficult if the oxygen was sufficiently expelled before packing.

  3. In 1999 I bought a full 18 wheeler trailer worth of food from Walden feeds, in the pails. So as we have used some of it over the years, I’ve been blessed with ample quantities of food grade pails and lids. I’ve used them to store things and because the main storage area is cool and dry, below ground level on two sides, I haven’t had a problem. But I should scout around and find some of these bags, they sound like something I should have to hand.

  4. I use an iron and a board to seal the mylar bags. I bought my bags from several sources. The one I used last was sorbent systems.

    I have wheat thats over 12 years old stored in this manner and its as freash as the day I bagged it.

    You can store just about any dry good using the bags.

    i cringe when i hear about people paying big money for things like beans and flour in cans when you can store your own for a fraction of the cost in bags and buckets.

  5. I am thinking of using a food saver and sealing smaller quantities of beans, flour, etc. with the oxygen absorbers and THEN storing those in Mylar bags in the 5 gallon buckets. My thought is that I can then open one bucket and use everything in that bucket before having to open another bucket. Any thoughts?

    • In my opinion you can eliminate the food saver step. What I do is store my dry goods in 1 gallon Mylar bags with an oxygen absorber. I then place the individual Mylar bags in a bucket. I take packets out as I need them without having to re-package everything. I also mix things up in a single bucket so – as you suggest – you can use up one bucket before moving on to the next.

      Using the Food Saver bags would add additional work and expense and is not needed since the combination of Mylar bag, oxygen absorbers, and a bucket will do the trick for you.

    • I used to store in 5 gallon buckets when my family was larger. My family is smaller, so I break up my storage into smaller quantities. I have 2 and 3 gallon buckets which now hold a day’s worth of food minus the liquid. By doing it this way, I know how many days of stores I have and how complete each one is. I reuse my chocolate chip mylar bags and store my sugar, salt, pepper and other spices in them for each bucket too. Of course they are relabeled. lol When disaster strikes or we suddenly want to go campning, we can just grab as many buckets as needed and go.
      Now I break up my storage into several locations. Should someone see one spot and take it, I’ve not lost ALL my stores. ;) Something I was taught by mountain men.

  6. I had understood that M is a composite of three elements, an outer plastic, foil and a plastic interior, where the foil produces oxygen barrier

  7. I am just wondering, if you buy freeze dried food in large cans, how long are they good for once you open the can? Would it be better to just portion them out into mylar bags for better storage if this is the case?

    • Most FD products in a large #10 tin have a stated shelf life of 1 year after they are opened. Depending on the product, I will repack a portion in smaller Mylar bags with an oxygen absorber or in a mason jar + oxygen absorber sealed with my FoodSaver jar attachment.

  8. Can you use mylar bags for short term cooked food storage. Actually, I know you can do it, but is it food-safe for this application?

    For example, I recently bought some Trader Joe’s Indian Faire meals that come in a mylar (or maybe it’s some sort of foil) pouch that you submerge in boiling water to heat, cut open and serve. The expiration date on these meals is well over a year and there are no food preservatives on the ingredient list.

    I’d like to cook rice and portion it into several mylar bags that I would keep in the fridge (I’d rather keep in a locker but I’m not sure if it will spoil) for a week or two (or maybe longer). Then I’d like to just submerge the rice-filled mylar pouch in boiling water to reheat it. I’ve seen plastic “boil-in-bag” pouches for this type of use, but I don’t want to cook my food in plastic and I’m not sure if mylar is any better.

    • Cooked food stored in that manner would be no different than food stored in a food saver bag. It will only be fresh under refrigeration for a short period of time. For longer term use, you would need to freeze the food in the pouch and then thaw and boil or try boiling from it’s frozen state. (I have not tried it.)

      The food pouches from Trader Joes may not have preservatives but they are probably dehydrated somehow. My guess is that the pouch allows moisture in so the food becomes moist during the boiling process – similar to military MREs that can go from dry to moist upon heating.

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