What are Mylar Bags?
The term Mylar is actually trademarked and produced by Dupont. Others have created these as well and they will carry the mylar name but are off-brand. This is akin to always calling a clear food storage bag with a zipper a Ziploc bag regardless of what brand it is.
Each Mylar bag is composed of layers of plastics and a layer of aluminum which stops any light or oxygen from penetrating and compromising the contents. They come in many different types such as ones that include an internal seal for resealing the contents, thicknesses, and kinds that are self-standing after opening (my personal favorite). You can even get multiple sizes that hold just a handful of ounces up to full 5-gallon bucket sizes.
These mylar bags are used in conjunction with an oxygen absorber packet that will remove oxygen from inside of the bag leaving mostly nitrogen which will keep your food safe and fresh. Properly sized oxygen absorbers and sealing methods should be used to ensure these work and are outlined below.
Dodge Counterfeit and Short-term Storage Bags
With the prevalence of counterfeit items, it’s hard to find a reputable source to purchase things these days. I would suggest not going all-in on buying bags from one source until you can verify the authenticity of the bags. For years now we have purchased only from a company named PackFreshUSA which has treated us very well and never provided a bad product. They have even provided us with a discount code for our readers. Just enter PREPPINGHQ during checkout!
The Type and Thickness of Bags
We tend to steer clear of bags with a clear window to see the contents. If it has a clear window, that portion is a possible fail point and also does not have the needed aluminum layer to protect your long-term supplies.
The thicker bags are costlier but I only purchase the 7 mil thick bags. You still have to be careful to not crinkle them too much and cause holes but I have not had any fail.
If your bag has a Ziplock-type seal ensure there is clearance above this to properly seal this for long-term storage.
Light Method
Shine a light through the wall of the bag. If light can be seen coming through it probably has an insufficient layer of aluminum or maybe aluminum plated. These will not work for long-term food storage.
Crinkle Method
If when bent or crinkled the bag bounces back as if it never happened, you are probably dealing with plated aluminum or painted plastic. The solid aluminum layer of a good bag will be much harder to smooth out creases.
What to Store in Mylar Bags
While most anything dry can be stored in mylar bags you must be aware that some caveats exist. Anything with a high-fat content will spoil such as nuts, raisins, and even brown rice will spoil. Also, anything with a higher than 10% moisture content could spoil very fast so those are not recommended. If dehydrating food ensure the end result is brittle and the food doesn’t bend.
We will be providing a list of foods to store in your Mylar Bags soon!
What Size Oxygen Absorber Should I Use?
A lot of mylar bags are sold as a set of bags with oxygen absorbers. These packets will actually absorb the oxygen from the sealed bag and leave behind nitrogen for preserving the contents.
We prefer to buy ones that are either individually packed or in no more than a pack of 10. They start absorbing air immediately so you have to work as fast as possible. Our method normally involves standing 10 bags, filling them, opening and dropping in the oxygen absorbers, and immediately sealing them.
Another method we have employed with success is dropping extras in a mason jar with a ring and lid for later. This is useful when dehydrating or freeze-drying as you may not have 10 bags worth of food.
The below guide should give you a base requirement for the size bags. This is based on the assumption of a full bag.
| Size Filled | Beans, Rice | Flour, Flax Meal, Coffee Beans, Mixes, Powder | Pasta, Dried Corn, Instant Potatoes, Oatmeal, Barley |
| Pint | 50cc | 50cc | 100cc |
| Quart | 100cc | 100cc | 150cc |
| 1/2 Gallon | 150cc | 200cc | 300cc |
| 5 Gallon | 1400cc | 2000cc | 2500cc |
A couple of items that can be sealed in mylar bags but should NOT have an oxygen absorber are salt and sugar. These will become solid chunks that are near impossible to work with (as we found out the hard way lol).
Sealing mylar bags
When we first started prepping (and before buying mylar bags) we had looked online for resources to help us decide on a sealing method. We ended up stealing my wifes’ hair straightener (like seen below) and carefully sliding it along each bag to seal. This method works great and we had zero failures from over 50 bags.
When purchasing a freeze dryer recently we were given an impact sealer (shown below) that produced an absolutely amazing and professional-looking seal in seconds. The price is a bit steep but had I known how much easier it would make the process I would have forked over some cash earlier.
When dealing with 5-gallon mylar bags you will have to resort to the hair straightener again as the width of the impact sealer isn’t enough. This is fairly easy to do and most bag suppliers give sufficient room above the bucket to be able to seal down 2-3″ from the top.
Storing Mylar Bags
To begin with, mylar bags should be stored inside of another pest-proof container with a secure and sealed lid. Airtight is not required since your bags will be sealed. Mylar itself is not rodent or pest-proof and can be easily chewed into ruining your supplies. We have used plastic totes, 5-gallon buckets, and even old kitty litter buckets to store ours.
Store your now-contained mylar bags in the coolest area possible. Most suggestions are 50-60°F (10-15.56°C) to extend the life of your dry goods. We keep ours in a basement that goes a bit above that but have had no trouble. A cupboard or closet is also a good option as it will be slightly cooler in these dark areas.
Tips:
- Don’t overfill your bags as it will make them much harder to seal.
- Think about portion sizes and opt for smaller bags or ones with a built-in method of resealing for items you will only use small amounts of at a time.
- Buy things in bulk and when on sales such as rice, beans, and even pasta.
- Have a few boxes or bags of dry goods to fill bags with to use all of the sealed Oxygen Absorbers you open.
- Save bags and cut off the sealed portion. They may be smaller but you can reuse and reseal them multiple times.