How to seal mylar bags with a vacuum sealer

Which sealers work with mylar

Mylar bags are smooth on the inside and thicker than most vacuum sealer bags. That affects which machines work well.

Do you need to vacuum mylar at all?

For most freeze dried and dry pantry foods, no. The standard method is to seal the bag with an oxygen absorber inside. The absorber removes oxygen, which is what drives staleness, rancidity and insect survival. Pulling a hard vacuum on freeze dried food can crush delicate pieces, and sharp items can puncture the bag.

Vacuuming helps with compact, dense foods where you want a tight package, and a chamber sealer does it gently because the bag only tightens at the end. Many people use a short or partial vacuum for that reason. See vacuum sealing vs mylar bags for how the two approaches compare.

Note.Oxygen absorbers and vacuum sealing are only for dry foods. Moist foods in low oxygen packaging can support Clostridium botulinum. Never use this method for fresh meat, cooked leftovers, or anything not fully dried.

How to seal mylar in a chamber sealer

A chamber machine handles smooth mylar because it empties the whole chamber, not just the bag opening. Our best vacuum sealers for mylar bags guide covers machines with chambers and seal bars suited to thicker bags.

1. 1

   Make sure the food is fully dry and at room temperature.

2. 2

   Fill the bag, leaving enough empty space at the top to lay the mouth across the seal bar.

3. 3

   Wipe the inside of the bag mouth clean.

4. 4

   Add the oxygen absorber last.

5. 5

   Place the bag in the chamber and set a longer seal time than you use for regular bags.

6. 6

   Use a lower vacuum setting for fragile foods.

7. 7

   Run the cycle, then inspect the seal and label the bag.

How to seal mylar with an impulse sealer

An impulse sealer sends a short burst of heat through a wire when you press the arm down, then cools while you hold it. Harvest Right sells one for its freeze dryer customers, and many similar models exist. Set the heat level for the bag thickness: too little heat leaves a weak seal that peels apart, and too much can melt through the bag. Test on an empty scrap first.

1. 1

   Fill the bag and add the oxygen absorber.

2. 2

   Press out excess air by hand, smoothing the bag toward the opening.

3. 3

   Lay the bag mouth flat across the sealing wire without wrinkles.

4. 4

   Press and hold the arm for the full heat and cooling time.

5. 5

   Inspect the seal. Add a second seal just above the first for extra security if you like.

How to tell if the seal is good

A good mylar seal is flat, even and continuous across the bag, with no wrinkles, channels or bubbles. Try to pull the two sides apart gently above the seal; it should not peel.

After sealing with an oxygen absorber, many bags pull in over the following hours to a day as oxygen is removed. Freeze dried food has a lot of air space and absorbers only remove the oxygen portion of air, so not every bag will look shrink wrapped. A bag that was tight and later goes loose may have a leak.

• Flat, even seal line with no wrinkles
• No crumbs or powder in the seal area
• Bag pulls in somewhat within a day
• No air escaping when you press gently on the bag
• Label shows contents, date and absorber size

Choosing bags and absorbers

Thicker mylar resists punctures better, which matters for pasta, rice and freeze dried meat. Choose a bag size you will use up within a reasonable time once opened. Size absorbers by the bag volume; our oxygen absorber size chart lists typical pairings.

Open a fresh pack of absorbers only when you are ready to seal several bags, and close the remaining absorbers in a small jar or vacuum bag immediately. Store finished bags in a cool, dark, dry place, ideally in a bucket. For the full routine, read how to store freeze dried food.

See mylar bag sealers →

Frequently asked questions

Can I use a FoodSaver to seal mylar bags? Many edge sealers can heat seal mylar with the seal only function, but they usually cannot pull a vacuum on smooth bags and may struggle with thick bags. Test on a scrap first.

Do I need the Harvest Right impulse sealer? No. Any impulse sealer suited to the bag thickness, or a chamber vacuum sealer, will seal mylar. The Harvest Right unit is one option.

Should I vacuum seal freeze dried food in mylar? It is optional. An oxygen absorber does the main work. A gentle chamber vacuum gives a tighter package but can crush delicate food.

How long do mylar bags last? Properly sealed mylar with an absorber and fully dry food in cool, dark storage is the standard for long term storage. Actual shelf life depends on the food and conditions; see how long freeze dried food lasts.