If you’ve ever unwrapped a shiny balloon or opened a sealed food pouch, you’ve met Mylar. But what really is it? And why do so many products use it?

The Short Answer: Mylar is a brand name for one specific polyester film made from stretched polyethylene terephthalate (PET). It's plastic that's processed to be stable, hard, and heat, gas, moisture, resistant. It's been the go-to material in nearly all industries for decades.

Due to its elasticity, shelf life, and barrier properties, Mylar pervades: in insulation and packaging, as decorations, and in archival storage.

Approximately 60% of Mylar films produced annually are for food and beverage packaging.

Here we'll take you through how we make Mylar, where we use it, what are its advantages and disadvantages, and some tips if you want to use it yourself.

How is Mylar produced?

Break the process down:

1. Extrusion and cooling

Liquid PET is pushed out and cooled to create a flat sheet.

2. Stretching (Orientation)

The film is stretched in one direction, then in the other direction perpendicular to that. This "biaxial orientation" aligns polymer chains and imparts strength and dimensional stability.

3. Heat setting / crystallization

With tension and heat, the film is "fixed in position" so that it will not contract or warp.

4. Optional metallization or coating

At times a layer of aluminium or other coating is added to improve barrier (to light, oxygen) or to create a reflective surface. 

Due to those treatments, Mylar is stabler and more resilient than uncoated PET.

Heat can be tolerated by Mylar film up to 302°F without melting.

The Key Features and Benefits of Mylar

Why not use Mylar instead of standard plastic? These are the things that really make it different:

Barrier protection: It prevents the entry of oxygen, water, and even light (particularly with its metallized finishes).

Tensile strength and tear resistance: It can withstand stretching, bending and tearing.

Thermal stability: It will support fairly high temperatures without melting and degrading.

Dimensional stability: It won't easily warp and shrink after processing.

Printability and finishing: It can be printed upon, laminated easily, coated, or even paired with zippers, resealable closures, etc.

Due to these, it is extensively utilized in packaging, insulation, and specialty applications.

Metallized Mylar reduces oxygen flow by around 96% when compared to standard plastic.

Common Applications (with Real-Life Examples)

Mylar will catch you when you least expect. These are just a few reasons why:

1. Food & Consumer Packaging

Custom mylar bags are used for dinner and snack packaging, coffee bag package, beef jerky pouches, anywhere freshness matters. Metallized Mylar keeps oxygen and light out.

Mylar excludes around 99.9% of the moisture from a bag.

2. Archival & Preservation

It is utilized to house valuable papers, maps, comics; stop moisture and stop aging. Libraries and collectors often employ Mylar.

3. Reflective Applications

Emergency "space blankets" use reflective Mylar to reflect body heat back. Mylar sheets are also used to insulate in electronics or building construction.

4. Decorative & Display

You have it in balloons, reflective decals and stickers, decorative overlays, craft, etc.

3. Electronics & Insulation 

Mylar is used as insulation film between conductive layers in electronics. Metallized Mylar finds application in the aerospace industry as part of multilayer insulation (MLI) to insulate spacecraft and satellites from temperatures.

The tensile strength of Mylar is about 25,000 psi, greater than the tensile strength of the same thickness foil.

Why Mylar Is So Widely Adored in Packaging

One of the greatest strengths of Mylar is the balance of protection and presentation that it strikes. It is light yet tough, and it can be paired with other layers; foil, paper, or polyethylene; to create multi-layered custom printed packaging that is suitable for any use.

Barrier performance: Dries, aromatizes, and maintains contents fresh.

Shelf appeal: Can be made glossy, matte, metallic clear, or holographic.

Customization: Facilitates fine digital printing and custom forms.

Resealability: Products with zippers, custom shapes, spouts, tear notches or even child resistant zippers for convenience to the consumer.

For food, supplement, candy or snacks and specialty firms, custom Mylar packaging provides the professional appearance and security traditional plastics cannot offer.

Mylar packaging will store food for 5 years when sealed tightly.

Challenges & Limitations

Mylar is not perfect. This is where it comes up short:

Cost

It's more costly to manufacture than regular plastics.

Recycling & disposal

Some Mylar films (particularly metallized or multi-layered) are difficult to recycle.

Sensitivity to sharp folds or scratches

As tough as it is, if you wrinkle or scratch it, barrier performance can be compromised.

Not completely impervious

With prolonged heat or extreme exposure, and degradation or gas permeability can find a way in.

When you're using Mylar, those compromises need to be balanced.

The market for Mylar is projected to exceed $31 billion by 2030.

Mylar vs. Foil: What's the Difference?

Mylar and aluminum foil are often confused with each other, but they are not interchangeable.

Mylar: Plastic-film based, flexible, and most commonly metallized. It adds strength, puncture resistance, durability and flexibility.

Foil: Solid aluminum-based, less flexible and crease-susceptible but provides full light and gas barrier.

Most modern pouches use both, Mylar laminated with foil, to offer best-in-class protection with flexibility.

Mylar deflects as much as 97% of light and heat, preventing damage from UV radiation and thermal fluctuations.

FAQs (People Ask)

1. Is Mylar waterproof?

Yes. Mylar is vapor- and waterproof, though not for full submergence.

2. Can you recycle Mylar?

Pure PET Mylar is occasionally recyclable along with plastic film, but metallized or laminated Mylar usually cannot.

3. How long can Mylar store food?

Sealed and stored in an airtight container and away from heat and light, Mylar bags are able to store food for several years.

4. Is Mylar biodegradable?

No, standard Mylar is not biodegradable, though biodegradable Mylar alternatives are available.

5. Does Mylar block UV light?

Yes, particularly metallized Mylar. It reflects up to 97% percent radiant energy, giving protection from UV damage.