Today 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 or, for an easier solution, try using use a hair straightening iron 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.
Enjoy your next adventure through common sense and thoughtful preparation!
Bargain Bin: Current picks related to this article.
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 one 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 Oven: 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): 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′ Black: 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.