If you store food, supplements, herbal products, or any retail goods, you have probably asked this question before: are Mylar bags airtight? The answer is: Yes, mylar bags are airtight when they are properly manufactured and sealed.
Now, the longer answer about whether these bags are air tight will get very interesting!
We can break down what air tight really means, how Mylar bags work, and when they fail!
What Does Airtight Mean in Packaging?
Airtight packaging is designed to prevent air and/or oxygen from entering or leaving the pack; therefore preventing product deterioration due to:
1. Exposure to oxygen
2. Intrusion of moisture
3. Loss of odor through leakage
4. Oxidation and staleness
For packages designed to be airtight, such as Mylar bags, the effectiveness of the package’s air-tightness is contingent upon both the physical structure of its material and its seal quality.
"Airtight performance in flexible packaging depends not only on the barrier properties of the film, but also on the integrity of the heat seal. When properly sealed, high-barrier laminate structures can effectively restrict oxygen and moisture transmission." - Dr. Susan E. Selke, Packaging Materials Specialist
Are Mylar Bags Themselves Airtight?
Indeed, Mylar bags possess natural airtightness that originates from their material properties.
The Mylar consists of a fine polyester film made from polymer resins with an aluminum foil laminated to the outside. Under this laminated structure is a food-safe polyethylene liner.
When these materials are combined into one Mylar bag, they form an extremely effective barrier against the following three potential sources of damage to the contents of those bags:
1) Oxygen transmission
2) Moisture vapors
3) Light exposure
Aluminum foil plays a critical role in achieving these high performance characteristics. Aluminum foil's ability to transmit oxygen through its thickness is close to zero (or no transmission). Because of this property, the Mylar bags provide excellent long-term storage of food, medical materials, and delicate items sold in retail settings.
The Seal Is What Makes or Breaks Airtight Performance
A Mylar bag will be completely airtight only if it has been properly sealed.
A Mylar bag will be considered properly sealed when:
- Sealed at the proper temperature using heat
- Sealed evenly along the entire top of the bag
- Sealed free of wrinkles, folds, or contaminants in the sealed area.
The most frequent reason that people believe that Mylar bags will not be airtight is due to poor sealing. Zippers alone do not create a true airtight seal; while it can be re-sealed, it is not a permanent seal.
Are Zipper Mylar Bags Airtight?
Here is usually where the confusion begins:
Zipper only = Not completely airtight
Zipper + heat seal = Completely airtight
Zipper is made for convenience and not for keeping out the air. If you want to keep your product looking fresh, tasting good and odorless for an extended period of time, then you need to seal the area above the zipper using a heat seal.
How Airtight Are Mylar Bags Compared to Other Packaging?
Mylar bags greatly exceed the performance of regular plastic or paper packaging and plain poly pouches.
Mylar bags outperform the following types of packaging:
- Standard plastic bags
- Kraft paper pouches
- Thin polyethylene packaging
If heat sealed properly and/or in combination with oxygen absorbers, Mylar bags are also equal in performance to vacuum sealed packaging.
If you want a deeper breakdown of the layers, materials, and science behind this barrier, you can read more about how Mylar packaging functions here.
When Mylar Bags Might Not Be Airtight
Even high quality Mylar bags can fail under certain conditions when:
- The seal temperature may be too low; or too high.
- The sealing bar may be uneven.
- Product debris may get trapped in the seal.
- The bag may be punctured or creased sharply.
Airtight performance involves many components, not just one material component.
Are Mylar Bags Airtight Enough for Long Term Storage?
Correctly heat-sealed Mylar bags provide excellent airtight packaging for long-term use.
They are often used for storing the following items:
* Foods, using oxygen absorbers
* Coffee and gourmet foods
* Flowers and concentrates
* Supplements and powders
* Emergency and survival supplies
Because of this, Mylar is still widely regarded as the highest-performing, most widely utilized type of packaging in numerous industries.
Why Brands are Switching to Airtight Customized Mylar Bags?
The demand for customized Mylar bags has increased significantly over the past few years due to the increased understanding of how much packaging affects the shelf life of products as well as how it impacts product presentation. Custom-printed Mylar bags have been recognized for their strength and barrier properties, specifically, they protect products from light, air, and moisture. This means that when a product is preserved in an airtight Mylar bag, its shelf life will be extended significantly by maintaining freshness, flavor, and potency; this is particularly important for food products, supplements, and cannabis products that are shipped in retail packaging. Another important aspect of custom-printed Mylar bags is that they give brands an effective way of promoting their brand identity through the use of bright colors and attractive designs printed on the bags.
Airtight customized Mylar bags offer brands an excellent opportunity to set themselves apart from competitors who sell similar products on retail stores or online. With the ability to be designed with graphic art, color, and message to fit each individual brand, companies can increase brand awareness at the same time that they are complying with labeling requirements set forth by regulatory agencies. Therefore, the combination of functional and aesthetic reasons makes it almost certain that airtight custom printed Mylar bags will continue to grow in popularity for companies that wish to present their products well while providing customers with high levels of satisfaction.
Final Answer: Are Mylar Bags Airtight?
Yes, Mylar bags are airtight when properly heat sealed and produced correctly. The material itself blocks oxygen and moisture extremely well. The seal determines whether that protection actually works.
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