Mylar bags: a foil barrier for dry food, sealed with heat
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Quick answer
Mylar bags are layered pouches of food-grade PET plastic and foil. Utah State University Extension says the foil layer dramatically reduces how much oxygen and moisture pass through. Fill them with dry, low-moisture, low-oil foods, add an oxygen absorber, and heat seal the top. A zipper alone is not airtight; Wallaby says to seal above it. Wallaby pairs its 1 gallon bags with 400 cc absorbers and its 5 gallon bags with 2,500 cc absorbers.
What Mylar bags are and why they work
- Layers: USU Extension describes these pouches as polyethylene terephthalate (PET) laminated with foil. The PET layer is food-grade plastic, and the foil blocks most oxygen and moisture.
- The name: Mylar is a trade name, USU notes, now used for this kind of bag generally.
- Light: Wallaby says its bags block light, air and humidity, three things that degrade stored food.
- Oxygen absorbers: USU recommends absorbers to remove oxygen, which extends shelf life and minimizes off-flavors in suitable dry foods.
Which foods go in Mylar, and which do not
| Food | Fit | Why |
|---|---|---|
| White rice, dry beans, pasta, wheat berries | Good | Low moisture and oil; Wallaby lists 25 to 30 years for low-moisture staples with absorbers |
| Brown rice, quinoa | Shorter term | Higher oil content; Wallaby suggests 1 to 2 years |
| Dried milk, flour, soup mixes, freeze-dried meals | Good when dry | USU lists Mylar-type bags or No. 10 cans with absorbers for dried milk |
| Moist or refrigerated foods | No | USU warns oxygen removal can help botulism bacteria grow in foods that need refrigeration |
| Home canning in pouches | No | USU says it requires special knowledge and equipment, and improper processing risks botulism |
USU's rule for oxygen-absorber packaging is foods that are low in moisture and oil content.
How to fill and seal Mylar bags
- Set up first: Wallaby suggests laying out food, bags, absorbers, your heat sealer and labels before you open the absorber pack, so absorbers do not lose effectiveness.
- Fill and partially seal: seal most of the top, leaving about a 6 inch opening.
- Add the absorber right before the final seal.
- Heat seal: Wallaby lists an impulse sealer (press 2 to 3 seconds), a metal hair straightener, or a clothes iron on the wool setting with one or two passes.
- Seal above the zipper: even zipper bags need a heat seal for long-term storage.
- Label with the food and date.
Wallaby cautions that most vacuum sealers do not get hot enough for Mylar and may seal before all the air is removed. Bags will not always look vacuum packed; the absorber removes oxygen, not all air.
Sizes and absorber amounts
- 1 gallon flat: Wallaby's are 10 x 14 inches, 5 mil per side, with 400 cc absorbers.
- 1 gallon gusset: stands upright for filling and shelf storage; 7.5 mil, with 400 cc absorbers.
- 5 gallon zipper: 20 x 30.5 inches, sized to line a 5 gallon bucket, with 2,500 cc absorbers. Wallaby says one holds about 35 to 40 pounds of rice or 33 pounds of wheat berries.
Wallaby ships absorbers in sealed packs of ten; reseal unused absorbers immediately. As a second layer, Wallaby suggests placing sealed bags inside a food-safe bucket to protect them from punctures and pests.
Storing and reusing bags
- Cool, dark place: Wallaby advises it, and USU notes that light quickly fades the color of stored beans.
- Reuse: Wallaby says you can cut a bag open below the old seal, refill it, add a new absorber and reseal.
- Rotation: shelf life claims are maker estimates; label and rotate, starting with higher-oil foods.
For drying food before storage, see our food dehydrator guides, and for liquids see our water storage containers guide.
What to look for when you buy
Stand-up gallon bags: Wallaby 1-Gallon Gusset Mylar Bags with Oxygen Absorbers
Best for: Pantry portions that stand on a shelf
Wallaby lists 7.5 mil BPA-free bags with a gusset base that stands upright, a zipper with room to heat seal above it, 400 cc oxygen absorbers in sealed 10-packs, and labels.
Watch out: Amazon lists thickness as 15 mil total; Wallaby's page gives 7.5 mil. Heat seal for long-term storage.
See options on Amazon (opens Amazon in a new tab)Bucket liners: Wallaby 5-Gallon Mylar Zipper Bags with Oxygen Absorbers
Best for: Bulk rice, wheat and beans in 5 gallon buckets
Wallaby lists 20 x 30.5 in bags, 5 mil per side with a foil lining, a zipper plus heat-sealable top, and 2,500 cc oxygen absorbers sized for up to 5 gallons of dry goods.
Watch out: Full bags are heavy, about 35 to 40 lb of rice per Wallaby.
See options on Amazon (opens Amazon in a new tab)Questions people ask
- What is a Mylar bag?
- A pouch of food-grade PET plastic laminated with foil; USU Extension says the foil layer dramatically reduces oxygen and moisture transmission.
- How do you seal Mylar bags with a clothes iron?
- Wallaby says to set the iron to wool and make one or two passes over the top edge, sealing above any zipper.
- What size oxygen absorber do I need?
- Wallaby pairs 400 cc absorbers with its 1 gallon bags and 2,500 cc with its 5 gallon bags.
- Can I store any food in Mylar bags?
- No; USU limits absorber packaging to foods low in moisture and oil, and warns about botulism risk in moist or refrigerated foods.
Sources
- Food storage packaging, Utah State University Extension
- How to Properly Seal Mylar Bags, Wallaby
- 1 Gallon Mylar Bags with Oxygen Absorbers, Wallaby
- 1 Gallon Gusset Mylar Bags with Oxygen Absorbers, Wallaby
- 5 Gallon Mylar Zipper Bags with Oxygen Absorbers, Wallaby