If you have ever used Mylar bags for food storage, supplements, cannabis, or retail packaging,

In reality "Mylar" doesn't actually mean that it's made out of aluminum. It is actually a brand name for biaxially oriented polyethylene terephthalate, often shortened to BoPET. In very simple terms, Mylar is a form of plastic film that has excellent tensile strength, good flexibility and dimensional stability. 

Mylar is:

* Clear/Translucent
* TearResistant
* Lightweight
* Excellent For Printing

Mylar is the plastic films that is the base material for a Mylar bag.

Where Aluminum Comes In

A thin layer of aluminum foil makes up a portion of the Mylar bag, which is a misunderstanding about Mylar bags. While the bag does appear to be metallic based on a visual inspection, Mylar bags do not consist of one solid aluminum sheet, but rather are made up of several layers that together create a laminated package; the overall structure of which typically looks like:

Outer layer: printed PET (Mylar)

Middle layer: aluminum foil or a metallized film

Inner layer: food safe polyethylene sealant

Although aluminium is a very thin layer, typically measured in microns, this layer performs an important function.

Since Mylar is a plastic based film, many people also ask about chemical safety. This is covered in more detail in our article on whether Mylar bags are BPA free.

Why Aluminum Is Used in Mylar Bags

The aluminum foil provides the highest level of protection, and when combined with the Mylar film (a highly durable polymer), it creates the high barrier package that sufficiently blocks the passage of:

- Light
- Oxygen
- Moisture
- Odor
- Flavors

Because of all these reasons, Mylar bags are typically used for long-term storage of food products, coffee, supplements, and other perishable or sensitive items. The aluminum layer serves the dual purpose of providing an opaque silver interior finish and increasing the shelf life of many items packaged within them.

Are All Mylar Bags Aluminum Foil Lined?

All Mylar bags don't contain aluminum as a component. 

There are a variety of types of Mylar bags: 

1. Clear Mylar bags with no aluminum lining; 

2. Metalized Mylar bags using vapor deposited aluminum (as opposed to foil); 

3. Foil Mylar bags containing a full aluminum foil inner lining; 

4. High-barrier laminated pouches with multiple layers of protection. 

Selecting the proper structure for your products is vital to knowing how long they will last after being packaged.

Metalized Film vs Aluminum Foil

It is also worth noting the difference between foil and metalized film.

Aluminum foil is a solid block of aluminum; it is very thin and has outstanding properties.

Metalized films are composed of plastics which have been coated with micro-sized aluminum particles.

Metalized film offers a balance between visibility, flexibility, and barrier protection, while full foil provides maximum shelf life and odor control.

So, Are Mylar Bags Made of Aluminum?

Yes, Many Mylar bags are made with aluminum, but they are not made entirely of aluminum, but many contain aluminum as part of a layered structure. The Mylar itself is plastic, while the aluminum layer enhances protection and durability.

Are Custom Mylar Bags Made of Aluminum?