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Mylar Bags, 4 Mil

SKU: WK928 Shop more Shannon Packaging items
$2.49 - $199.95
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Mylar bags are a special type of metalized vacuum-sealable bag. Just like standard vacuum bags, they have an inner layer of FDA approved food safe polyethelene. The poly layer has a relatively low melting point, so it can be heat-sealed to close the bag air tight. Fused to the outside of the poly layer is a layer of nylon that acts as a strong barrier to oxygen soak-through (a far better barrier than poly). Nylon cannot be heat-sealed, but the duo of poly and nylon is heat-sealable and highly impermeable to oxygen. What distinguishes Mylar bags is a third layer of thin, flexible metal fused to the outside of the nylon layer. This thin metal layer provides the ultimate oxygen barrier. And outside the metal layer is another polymer layer for abrasion resistance. Mylar bags are the best choice for multi-year oxygen-free storage of food (or other goods). They also provide the maximum barrier against moisture and any vapors that may be in the storage environment, including possible fuel vapors. Mylar bags are normally used as liners inside a rugged container (typically a quality plastic bucket) that will protect your goods and the Mylar bag from physical damage (including damage from vermin).


These durable 4 mil thickness Mylar bags are pre-sealed on three sides to form the bag. The 20 x 30 inch bags are sized for use inside either a 5 or 6 gallon bucket, leaving enough bag sticking out the top, to be heat sealed. The 8 x 12 inch bags have a 1-quart capacity. 

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First step: Sealing the bag

Two steps must be taken to protect your food with Mylar bags. One is that you must seal the bag, and the other is that you must get the oxygen out. Sealing the bag can be done with a commercial impulse sealer. That's a machine that fuses the bag mouth shut. A straight impulse sealer does NOT vacuum air out of the bag, it just seals it shut.  Commercial impulse sealers are available with wide enough seal bars to span the full 20" width of the large Mylar bags. Another way to seal the bag shut is to use a common household "Seal-a-Meal" type of machine. Those machines are normally used (with smaller bags) to both extract air AND to seal a bag shut. Such home-use vacuum-sealing machines don't have a wide enough opening to extract the air from a 20" wide bag, but they CAN seal such a wide bag opening shut (without air extraction), by using their "seal only" mode and simply sealing multiple connecting bands across the full width of the bag opening. A fairly large home vacuum sealer can seal a 20" wide bag using that method, in just two "bites." It's less convenient than the commercial impulse sealer, but it does offer the advantage of versatility... meaning that when you're not sealing 20" wide Mylar bags, the "Seal-a-Meal" type of machine can be used to seal lots of products (with or without vacuuming out the air) in smaller bags as well as other types of containers. It's an excellent way to greatly extend the fresh taste and nutrient quality of foods on the counter, or in the fridge or freezer, by eliminating the rapid degrading effects of oxygen. (Important clarification: Home-type vacuum sealers, in order to extract air from the bag, require use of plastic bags having an embossed inside surface. BUT if you only want to seal a bag and not use it to extract air, then home-type machines WILL accomplish that sealing function on smooth-surfaced bags like the Mylar bags, that do not have an embossed surface.)

The second step (oxygen removal)

You could spend $8,000 on a huge chamber-style vacuum machine designed to vacuum-extract the contents of a large bucket, and seal the Mylar bag. A much less expensive route, and one that's equally effective, is to simply put one or more oxygen absorber packets into the bag before you seal the bag closed. For small-scale operations, oxygen absorbers are highly economical, reliable and easy to use.

Interestingly... there's a reason why these bags look like Mylar party balloons. It's because they're made of a commercial version of the same material as the balloons. Helium is an extremely tiny atom, even for a gas. In an ordinary latex balloon, a special chemical coating must be added to keep the helium corralled... without that coating, the helium atoms holler "Adios, we're outta here" and zip right out through the balloon's wall, leaving it shriveled and very un-party-like. Whether or not helium contacts your food is irrelevant, because helium is highly inert. But Mylar's ability to stop the passage of even tiny helium atoms is great testimony to its effectiveness against much larger molecules including O2 and H2O!

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BrandShannon Packaging
Product ColorSilver
BPA FreeYes


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