01Mylar is a trademark, "mylar bag" is a market name
MYLAR is a registered US trademark for polyester film (Reg. No. 559,948, registered June 10, 1952), with DuPont Teijin Films US, a limited partnership, as the owner of record at the USPTO. In February 2024 the company changed its trading name to Mylar Specialty Films, still a joint venture of Celanese and Teijin. It says Mylar was introduced in the 1950s as the world's first biaxially oriented PET film.
The film itself is BoPET: biaxially oriented polyethylene terephthalate, a polyester film stretched in two directions. Sellers use "mylar bag" generically for foil and metallized PET pouches, and a bag sold as mylar is not necessarily made with Mylar film. On this page we say "foil or metallized PET bags (sold as mylar bags)". Describe the material on your listing, not the brand, unless the supplier's spec sheet names Mylar film.
02The three structures you will be quoted
A mylar bag laminates several films, each doing one job. In a typical foil pouch, an outer biaxially oriented polyester layer protects the aluminum foil from being punctured, and the inner sealant layer is the one that touches the food.
| Structure | What it is | What to know |
|---|---|---|
| Metallized PET (MET PET) / PE | PET film coated with a vacuum-deposited aluminum layer a few hundred angstroms thick, laminated to a PE sealant | Opaque to light, good oxygen and moisture barrier; may need a third layer to heat seal well |
| PET / aluminum foil / PE | A real sheet of aluminum foil between an outer PET film and an inner sealant | Outstanding barrier on flat film, but foil laminates can crack and pinhole when flexed |
| Clear PET / PE | No metal layer | Shows the product; no light barrier and no metal layer, so ask for its OTR |
A film maker writing in Packaging Strategies put the trade-off plainly: foil is known for outstanding barrier but not for flex-crack resistance, and once a foil lamination is flexed, it can crack and pinhole and let more gas through. Metallized PET typically has a good oxygen and moisture barrier but doesn't always seal well on its own, so it often goes into a three-layer laminate. For a bag that gets shipped and squeezed, ask for barrier data after a flex test.
03Why light and oxygen barrier matter
Among the factors that shorten food's shelf life, Utah State University Extension lists temperature, moisture, oxygen and light. Oxygen drives oxidation in stored food, and light degrades fats, proteins and the fat-soluble vitamins A, D and E. Opaque packaging cuts the light that reaches the food, and USU lists foil pouches among the containers with an airtight seal. A foil or metallized bag is opaque, and sealed, it slows oxygen. The barrier is only as good as the seal and any window, so inspect seals on the pre-production sample.
04Oxygen absorbers and the 10 percent rule
Oxygen absorbers are small packets of iron powder that react with oxygen and moisture in a sealed container, according to Oregon State University Extension. Air is about 78 percent nitrogen and 21 percent oxygen, so once the oxygen is absorbed what is left is mostly nitrogen in a partial vacuum, USU Extension explains.
If you sell food, USU warns that botulism can occur if moist products are stored in packaging that reduces oxygen, and that food stored in airtight containers with oxygen absorbers must be dry: about 10 percent moisture or less. If your product is not a dry food, don't use oxygen absorbers or low-oxygen packaging until a food safety specialist or process authority has signed off on it.
05Food contact: what to ask for, not "FDA approved"
FDA food-contact rules work at the level of substances and their conditions of use, not finished bags:
- 21 CFR 177.1630 covers polyethylene phthalate polymers, including PET films for food contact, with conditions such as temperature and food type.
- 21 CFR 177.1520 covers olefin polymers, including the polyethylene and polypropylene used as sealant layers.
- 21 CFR 175.105 covers adhesives. Where an adhesive is not behind a functional barrier, its contact with fatty and aqueous foods is limited to trace amounts at seams and laminate edges.
- 21 CFR 174.5 requires food-contact substances to be of a purity suitable for their intended use, and says packaging that makes food unfit, for example through odor or taste, still violates the law.
- A food contact notification (FCN) covers only the manufacturer or supplier named in it.
Ask the bag supplier for a letter of guaranty or compliance statement that names these regulations, your food type and your fill and storage temperatures. Write "made of materials that comply with 21 CFR 177.1630 and 177.1520 for the intended use", never "FDA approved".
06Thickness, zippers, smell-proof and child-resistant claims
Thickness. Bags are quoted in mil (one thousandth of an inch, 25.4 microns) or microns. A "mil" figure on a listing may mean one wall or both walls added together, so ask, and ask for each layer's thickness. Compare barrier data, not just mil.
Zippers. Treat the heat seal as the barrier and the zipper as a way to reclose.
Smell-proof. That is a listing description, not a tested rating. Ask what test and conditions back it, then seal your own product in samples and check.
Child-resistant. The US rules are in 16 CFR 1700. Products on the list in 1700.14 need special packaging, including dietary supplements with 250 mg or more of elemental iron in a single package and oral prescription drugs, with listed exceptions. That packaging must pass the 1700.20 test: panels of children aged about 42 to 51 months and of adults aged 50 to 70. Under 1700.15, at least 85 percent of children must fail to open it without a demonstration (80 percent after), and senior adult use effectiveness must be at least 90 percent. A zipper sold as child-resistant needs a test report for that package, not just a zipper spec.
07Recyclability
A foil or metallized PET bag bonds PET, aluminum, adhesive and a polyolefin sealant into one sheet. Under the FTC Green Guides (16 CFR 260.12), an unqualified "recyclable" claim needs recycling programs available to at least 60 percent of consumers where the item is sold, and if any component significantly limits recycling, a recyclable claim is deceptive. Don't print a recycling claim on a mylar bag unless the supplier can give you evidence that meets the Guides. If recyclability matters more than barrier, ask what single-material structures it offers and compare them on our sustainable packaging page.
08When to choose a mylar bag
- Dry food for long-term storage, with oxygen absorbers: a foil laminate (PET/AL/PE), heat sealed. Only for food at about 10 percent moisture or less.
- Coffee, snacks, supplements and powders on a retail shelf: metallized or foil, for example as a stand-up pouch. Ask for barrier data and run a shelf-life test with your product.
- Single servings: see sachets and stick packs.
- Product you want customers to see, short shelf life: clear PET/PE, or a window, accepting less barrier.
Minimums depend on the print method, the number of designs (SKUs) and whether the size is a stock size. Ask each supplier for its minimum per design, the plate or setup charge, and the unit price at two quantities. See what MOQ means. The Vault lists packaging suppliers with their contacts.
09Before you sign off
- Fill a sample with your real product, seal it and leave it for a few weeks before you approve. Check for pinholes, seal leaks and odor.
- Compare quotes on the structure line, not the word "mylar".
- Get the compliance letter and barrier data with the quote.
- If your product is on the 16 CFR 1700.14 list, get the child-resistant test report before you approve print.
10How to spec it with a supplier
Quotes are only comparable when the spec is. Write it out, with a dieline.
| No. | Field | What to write |
|---|---|---|
| 01 | Format | Flat, stand-up, side gusset or flat bottom; with dieline and fill weight |
| 02 | Dimensions | Width x height x gusset in mm, with tolerance; state inside or outside |
| 03 | Structure | Each layer in order, outside to inside, with thickness (for example PET / AL foil / PE); state metallized or foil |
| 04 | Barrier | OTR (ASTM D3985) and WVTR (ASTM F1249) at stated conditions, flat and after a flex test |
| 05 | Food contact | Compliance letter naming 21 CFR 177.1630, 177.1520 and 175.105, your food type and temperatures |
| 06 | Closure | Heat seal only, press-to-close zipper or child-resistant zipper (with 16 CFR 1700.20 test report); tear notches; hang hole |
| 07 | Seal | Seal width and minimum seal strength, checked on samples |
| 08 | Method, CMYK and Pantone references, matte or gloss areas, window position if any | |
| 09 | Packing | Bags per carton, carton size and weight |
| 10 | Samples | Printed proof and a pre-production sample from the production line |
11FAQ
Q01What is a mylar bag made of?
Typically outer PET, an aluminum layer (metallized coating or foil) and an inner sealant such as polyethylene.
Q02Are mylar bags really Mylar?
Not necessarily. Mylar is a registered trademark for a polyester film, and "mylar bag" is used for foil and metallized PET pouches whatever film they use.
Q03Are mylar bags food safe?
They can be, if the materials comply with FDA rules such as 21 CFR 177.1630 and 177.1520 for your food and temperatures. Ask the supplier for a compliance letter naming those regulations.
Q04Do I need oxygen absorbers in mylar bags?
For dry food stored long term, USU Extension says airtight containers with oxygen absorbers keep out insects and help preserve quality. Use them only with dry food, about 10 percent moisture or less, because of the botulism risk.
Q05Are mylar bags smell-proof?
"Smell-proof" is a listing description, not a tested rating. Ask what test backs it, and check sealed samples with your product.
Q06Are mylar bags recyclable?
Not in household recycling bins: they are multi-material laminates, and the EPA says plastic bags and film can't go in household bins. Don't claim "recyclable" without evidence that meets the FTC Green Guides.