How to Seal Mylar Bags for Food Storage: A Step-by-Step Guide

Optimize dry food storage with our Mylar bag sealing guide. Explore expert tips, essential tools, and step-by-step techniques for freshness.

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Mylar bags are a great way to store dry foods for long periods of time, as they protect them from oxygen, moisture, light, and pests. In this post, I will show you how to properly fill and seal mylar bags using different methods and tools. Let’s get started!

Page Contents

What is a Mylar bag and why is it used?

Mylar bags are made of a thin layer of polyester film coated with aluminum foil. They are also known as metalized bags or foil pouches. Mylar bags have several advantages over other types of food storage containers, such as plastic buckets, glass jars, or ziplock bags. Some of these advantages are:

Mylar bags are lightweight and flexible, which makes them easy to store and transport.
Mylar bags are durable and puncture-resistant, which means they can withstand rough handling and prevent rodents or insects from getting into your food.
Mylar bags are opaque and reflective, which means they block out light and heat, which can degrade the quality and shelf life of your food.
Mylar bags are impermeable to oxygen and moisture, which means they prevent oxidation and mold growth, which can spoil your food.

Mylar bags are ideal for storing dry foods that have low moisture and oil content, such as grains, beans, rice, pasta, nuts, seeds, spices, herbs, dried fruits, and dehydrated foods. These foods can last for up to 25 years or more if stored properly in mylar bags with oxygen absorbers. Oxygen absorbers are small packets that contain iron powder or other substances that react with oxygen and remove it from the air inside the bag. This creates a vacuum seal that preserves the freshness and flavor of your food.

How to Fill and Seal Mylar Bags

There are different ways to fill and seal mylar bags, depending on the size of the bag, the type of food, and the tools you have available. Here are some general steps to follow:

Label the bag. Before you fill the mylar bag, use a permanent marker to write the name of the food, the date of packaging, and any other information you want to remember, such as the cooking instructions or the intended use. This will help you identify and organize your food storage later.

Fill the bag. Stand the bag upright and open it wide. Then, pour or scoop the food into the bag, leaving about 3-4 inches of space at the top. You can use a funnel, a measuring cup, or a ladle to make this easier. You can also place the bag in a bucket or a bin to keep it stable while filling. Do not mix different kinds of foods in the same bag, as this can affect their shelf life and taste.

Add oxygen absorbers. Place one or more oxygen absorbers on top of the food inside the bag. The amount of oxygen absorbers you need depends on the size of the bag and the type of food. As a general rule, you should use at least 100 cc of oxygen absorbers per quart of food. For example, for a one-gallon bag, you would need at least 400 cc of oxygen absorbers. For a five-gallon bag, you would need at least 2000 cc of oxygen absorbers. You can find oxygen absorbers online or in some specialty stores. They usually come in sealed packages that you should open only when you are ready to use them. Otherwise, they’ll lose their effectiveness.

(Some alternatives to oxygen absorbers are:

Hand warmers:These are small packets that contain iron powder and other substances that react with oxygen and generate heat. They are similar to oxygen absorbers, but they are designed to create warmth rather than to preserve food. Some people use hand warmers instead of oxygen absorbers for food storage, as they are cheaper and more widely available. However, hand warmers may not be as effective or reliable as oxygen absorbers, as they are meant to work under different conditions and with different amounts of oxygen ¹ ².
Food grade iron powder:This is a natural and safe alternative to chemical components in oxygen absorbers. It is a fine powder that reacts with oxygen and forms iron oxide, which is harmless and edible. Food grade iron powder can be used to make DIY oxygen absorbers by mixing it with salt and water and placing it in a small cloth bag. It can also be added directly to food products, such as flour, spices, or nuts, to prevent oxidation and extend shelf life ³.
Vacuum sealing:This is a method of removing air from a container or a bag before sealing it. Vacuum sealing reduces the amount of oxygen and moisture in the package, which slows down the growth of bacteria and mold. Vacuum sealing can be done with a vacuum sealer machine or with a manual pump. Vacuum sealing can also be combined with oxygen absorbers for extra protection ⁴ )

Heat-seal the bag. There are different tools you can use to heat-seal the bag, such as a clothes iron, a hair straightener, a clamshell heat sealer, an impulse heat sealer, or a vacuum sealer. The idea is to apply heat and pressure to the top edge of the bag to fuse the layers of plastic and foil together and create an airtight seal. Here are some tips for each tool:
Clothes iron: Set the iron to the highest setting and let it heat up. Then, place a piece of wood, cardboard, or towel under the bag to protect the surface. Fold the top edge of the bag over the wood or towel and press the iron firmly along the edge. Move the iron slowly from one end to the other, making sure to cover the entire width of the bag. Repeat this process until the bag is sealed. You can also use a portable ironing board or a timber wrapped in a towel to make this easier.

Hair straightener: Plug in the hair straightener and let it heat up. Then, clamp the hair straightener over the top edge of the bag, overlapping the edge by about an inch. Slide the hair straightener quickly and carefully along the edge, making sure to cover the entire width of the bag. Repeat this process until the bag is sealed. You can also use a flat iron or a curling iron for this method.

Clamshell heat sealer: Plug in the clamshell heat sealer and let it heat up. Then, place the top edge of the bag between the jaws of the sealer and press the handle down. Hold it for a few seconds until the indicator light turns off. Release the handle and remove the bag. Repeat this process until the bag is sealed. You can adjust the temperature and the pressure of the sealer according to the thickness of the bag and the type of food.

Impulse heat sealer: Plug in the impulse heat sealer and let it heat up. Then, place the top edge of the bag between the jaws of the sealer and press the handle down. Hold it for a few seconds until the indicator light turns off. Release the handle and remove the bag. Repeat this process until the bag is sealed. You can adjust the temperature and the duration of the sealer according to the thickness of the bag and the type of food.

Vacuum sealer: Plug in the vacuum sealer and turn it on. Then, place the open end of the mylar bag into the vacuum chamber of the sealer. Press the seal button and wait for the sealer to suck out the air and seal the bag. Remove the bag and test the seal. You can also use the manual mode of the sealer to control the amount of vacuum and the sealing time.

Some tips for heat-sealing the bag are:

Start with a partial seal. Seal the middle part of the bag first, leaving some space on both ends. Then, squeeze out as a great deal air as feasible from the bag. Finally, finish sealing the ends of the bag.
Check the seal. After sealing the bag, inspect the seal for any gaps, holes, or wrinkles. If you find any, reseal the bag or use a new one. You can also test the seal by gently pressing on the bag and listening for any hissing sounds, which indicate air leakage.
Store the bag. After sealing the bag, store it in a cool, dry, and dark place, away from direct sunlight, heat sources, and pests. You can also place the bag in a bucket or a bin for extra protection and convenience.

Some common mistakes to avoid when sealing mylar bags are:

Not labeling the bag before filling it. This can lead to confusion and misidentification of the food later. You should write the name of the food, the date of packaging, and any other relevant information on the bag with a permanent marker ¹.
Mixing different kinds of foods in the same bag. This can affect their shelf life and taste. You should only fill the bag with a single type of food item ¹.
Not using enough oxygen absorbers for the size of the bag and the type of food. Oxygen absorbers are small packets that remove oxygen from the air inside the bag and create a vacuum seal that preserves the freshness and flavor of the food. You should use at least 100 cc of oxygen absorbers per quart of food ¹ ².
Not allowing the heat source to heat up sufficiently before sealing. The heat source, such as a clothes iron, a hair straightener, or a heat sealer, should be set to the highest setting and let it heat up for a few minutes. If the temperature is not high enough, the mylar will not seal. If it is too high, the mylar will melt ³ ⁴.
Not checking the seal for any gaps, holes, or wrinkles. After sealing the bag, you should inspect the seal for any defects that could allow air to enter the bag. If you find any, you should reseal the bag or use a new one. You can also test the seal by gently pressing on the bag and listening for any hissing sounds, which indicate air leakage ¹ ².
Not storing the bag in a cool, dry, and dark place. After sealing the bag, you should store it away from direct sunlight, heat sources, and pests. You can also place the bag in a bucket or a bin for extra protection and convenience ¹ ².

FAQs

Q: What size of mylar bags should I use for food storage?

A: The size of the mylar bags you should use depends on the amount and type of food you want to store, as well as the space and convenience you have. Generally, smaller bags are easier to handle, store, and rotate, while larger bags can hold more food and save on oxygen absorbers. Some common sizes of mylar bags are:

1 quart:This size can hold about 1.5 pounds of dry food, such as rice, beans, or pasta. It is suitable for individual or small family servings, or for storing spices, herbs, or dried fruits.
1 gallon:This size can hold about 6 pounds of dry food, such as grains, legumes, or nuts. It is suitable for larger family servings, or for storing flour, sugar, or salt.
5 gallon:This size can hold about 30 pounds of dry food, such as wheat, corn, or oats. It is suitable for bulk storage, or for storing animal feed, seeds, or charcoal.

Q: How long can food last in mylar bags?

A: The shelf life of food in mylar bags depends on several factors, such as the type and quality of food, the amount of oxygen and moisture in the bag, the temperature and light exposure of the storage area, and the presence of pests or rodents. Generally, dry foods that have low moisture and oil content, such as grains, beans, rice, pasta, nuts, seeds, spices, herbs, dried fruits, and dehydrated foods, can last for up to 25 years or more if stored properly in mylar bags with oxygen absorbers. Foods that have higher moisture and oil content, such as dairy products, meats, eggs, or oils, can last for a shorter time, ranging from a few months to a few years, depending on the processing and packaging methods.

Q: How can I tell if my mylar bags are sealed properly?

A: There are several ways to check if your mylar bags are sealed properly, such as:

Visual inspection:After sealing the bag, inspect the seal for any gaps, holes, or wrinkles. If you find any, reseal the bag or use a new one. You can also test the seal by gently pressing on the bag and listening for any hissing sounds, which indicate air leakage .
Weight measurement:After sealing the bag, weigh it and compare it to the weight of the bag before sealing. If the weight has decreased, it means that some air has been removed from the bag. If the weight has increased, it means that some air has entered the bag. You can also use a digital scale that measures in grams or ounces to get a more accurate reading.
Water submersion:After sealing the bag, submerge it in a bucket or a sink filled with water. If the bag floats, it means that there is still some air inside the bag. If the bag sinks, it means that there is no air inside the bag. You can also look for any bubbles coming out of the bag, which indicate air leakage.

Q: How can I reseal my mylar bags after opening them?

A: If you want to reseal your mylar bags after opening them, you need to follow the same steps as when you first sealed them, such as:

Label the bag:Write the name of the food, the date of resealing, and any other information you want to remember on the bag with a permanent marker.
Fill the bag:Pour or scoop the food back into the bag, leaving about 3-4 inches of space at the top. Do not mix different kinds of foods in the same bag, as this can affect their shelf life and taste.
Add oxygen absorbers:Place one or more oxygen absorbers on top of the food inside the bag. The amount of oxygen absorbers you need depends on the size of the bag and the type of food. As a general rule, you should use at least 100 cc of oxygen absorbers per quart of food .
Heat-seal the bag:Use a heat source, such as a clothes iron, a hair straightener, a heat sealer, or a vacuum sealer, to seal the top edge of the bag. Apply heat and pressure to the edge to fuse the layers of plastic and foil together and create an airtight seal. Check the seal for any gaps, holes, or wrinkles. If you find any, reseal the bag or use a new one .

Q: What are some tips and tricks to make sealing mylar bags easier and faster?

A: Some tips and tricks to make sealing mylar bags easier and faster are:

Use a funnel, a measuring cup, or a ladle to fill the bag:This can help you avoid spilling or wasting food, and make the filling process more efficient and accurate.
Use a bucket or a bin to hold the bag while filling and sealing:This can help you keep the bag stable and upright, and prevent it from falling or tipping over.
Use a portable ironing board or a timber wrapped in a towel to seal the bag:This can help you protect the surface underneath the bag, and provide a flat and smooth surface to seal the bag.
Use a rubber band or a clip to hold the bag closed while sealing:This can help you keep the bag closed and prevent air from entering the bag while sealing.
Use scissors or a knife to cut off the excess material after sealing:This can help you reduce the size and weight of the bag, and make it easier to store and handle.

Conclusion

Mylar bags are a great way to store dry foods for long periods of time, as they protect them from oxygen, moisture, light, and pests. To seal mylar bags, you need to label the bag, fill the bag, add oxygen absorbers, and heat-seal the bag using different tools and methods. By following these steps, you can ensure the freshness and quality of your food for years to come.