Are Mylar bags Airtight and Waterproof

Last Updated on July 13th, 2023

We may earn commissions for purchases made through links on our site. Learn more on our about us page.

When Mylar was first produced around sixty or so years ago, it was designed to protect astronauts and space equipment from the dangerous solar radiation and UV rays zipping about in space. 

In effect, the inventor created an airtight, heat-retentive, and waterproof material.  In short, yes, Mylar bags are known for being the leaders in long-term dry food and goods storage and providing adaptable products for business and family needs. 

One of the necessary components needed for this to be possible is a material that is non-permeable, especially when it comes to air, microorganisms, and water molecules. 


Do Mylar Bags Keep Moisture Out?

To put this in perspective, most waterproof materials will allow smaller microorganisms or air molecules through. However, airtight materials can only do so much when it comes to photons and smaller pieces of energy. 

Mylar has the ability to shield out the Sun’s photonic radiation and UV light molecules, making it one of the most secure, non-permeable materials invented by humanity. 

In short, yes, the Mylar bag is very adaptable at keeping liquids out and preventing moisture damage to the inner contents. 


Can you Air-Seal Mylar Bags?

When it comes to sealing these bags, there are two ways to go about it, and many will go with the zipper feature that allows for recycling and reusing of the Mylar packaging. 

This will provide a satisfactory air and moisture seal for snacking foods, dry goods, and other daily consumption items. 

The other designs of bags will be without a zipper and be for single-use purposes, such as medications or other daily consumption products. 

Either form of Mylar bag will have the ability to be heat sealed, which will create the air seal desired by the business or family member. 


How Waterproof are These Bags?

As mentioned in the article, the Mylar polyethylene terephthalate (PET) material was designed to shield astronauts and millions of dollars of equipment from the Sun’s radiation and UV rays. 

In addition, the subatomic particles known as photons are considered to be much smaller than those of the water molecule, which then teaches us that these materials will be waterproof. 

Where the issue might be found in the quality of the zipper technology, which is for closing and reopening packages more easily, over time this seal can break down, causing the bags to become non-waterproof in some instances, to which it can be given a 9, plus out of ten. 


For How Long Can a Bag Stay Waterproof and Airtight?

When it comes to the integrity of the mylar and aluminum partnership that goes into the space tech and storage packaging of these bags, there is no question that Mylar stays both airtight and waterproof for the better of fifty years or so. 

The issue lies, as mentioned above, with the zipper and the durability of the sealing tech. 

When it comes to the multiple usage rates of these types of bags, the contents and the ‘clogging factor’ when it comes to the grooves of the zippers, and how rough the user is with the packaging as a whole. 

How long depends on these and other factors when it comes to interaction with the packaging. 


What is the Best Way to Seal it?

The first step will be to ensure the inside is clean, place it in a five-gallon bucket, then fill it with the desired products. Next will be to close the bag zipper, if applicable, and then provide a heat seal on the outer lips of the opening. 

After that, allowing any oxygen absorber packets to do their job, these bags will almost be sucked into the buckets, to which a prepper will want to use a rubber mallet to close a lid tightly over the Mylar packaging. 

This is the right way to go about storing dry goods and foods. There will be other processes when it comes to shorter-term storage needs and projects. 


Final Thoughts on Are Mylar Bags Airtight and Waterproof

There is very little to worry about when you use these Mylar bags for storage of foods and goods, for both short-term and long-term needs. 

These materials will be impermeable when it comes to the elements and can be backpackers’ and outdoor adventure enthusiasts’ new favorite packaging solution, let alone the military and any exploration efforts. 

Just to add to the level of assurance when using the Mylar product, these bags are nearly completely puncture-proof and require immense amounts of pressure to push sharp blades through the walls of these bags.