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What is Glassine?

What is Glassine?

Apr 21st 2022

In 2020, we launched an exciting new offering - Glassine Bags for inner or wholesale packaging. This week we released Version 2.0 of this bag. Our latest version is a huge step forward - it is flat (not gusseted), has vent slits, not holes, and has side seams that are much sleeker. 

These glassine bags are still a great paper-based alternative to the clear poly bag at their core. They are part of EcoEnclose’s Inner Packaging Line, which helps product goods (often apparel) in transit from the factory to the distribution center to the end consumer. Most brands default to using clear poly bags for this inner packaging. But, as more and more brands seek to eliminate plastic packaging from their operations - many are rethinking the poly bag and wondering, are there more renewable, more recyclable, more circular options.

We have three paper-based options to choose from: Vela Glassine Bags | 100% Recycled Kraft Bags | 100% Recycled EcoBands

Our Glassine Bag is the most unique and visually appealing poly bag alternative. Why? Because glassine is an incredibly cool material!

What is glassine?

You actually see glassine all the time as you go about your life. Here are some common examples: 

glassine bag, glassine merchandise bag

Bakery and snack bags

Merchandising

Archival paper

Tracing paper

Art protection sheets or bags

And now...product and apparel protection

How is glassine made?

Glassine is smooth and glossy paper that is air, water, and grease resistant. It is important to note that glassine is not fully waterproof! If you dump a glass of water on it, water will seep through. But in the ordinary course of events, glassine offers good resistance against atmospheric elements.

And, yes, despite how it feels and looks, it is made with 100% wood pulp!

Glassine is manufactured through a unique process called supercalendering.

super calender machine for glassine

Source: Valmet

supercalendering glassine

First, wood is turned into pulp (as with any paper). Trees are chipped, and these wood chips are cooked to break the chemical bond of the lignin so pulpers can separate the cellulose. Unlike most other papers, glassine paper production requires a fully complete lignin separation. This pulp slurry is then bleached and treated, then flowed through a moving wire cloth where the water drains out. The fibers mat and intertwine as paper sheets begin to take form.

Once dried, this material is then “calendered” or pressed between hard pressure cylinders called calendars. At that point, the standard paper is complete.

Glassine goes one step further through a process called supercalendering. The paper is put through the calendering process multiple times, typically on a particular machine with heated or cooled pressurized calendars. This process causes the fibers of glassine to all be facing the same direction.

This process isn’t just basic “pressing,” as the process changes the paper on a cellular level. The capillaries of the paper fibers are broken down, giving it higher density, low porosity, and a glossy finish.

How is glassine different from standard paper?

Resistant to moisture and grease: Standard paper absorbs water. Technically, paper absorbs water vapor from the air through a process called hygroscopicity, which causes the substrate to expand or contract based on the relative humidity of its surroundings.

The supercalendering process that changes the cellulose of glassine makes it less susceptible to hygroscopicity.

Durable and stronger than standard paper of the same weight: Because glassine is denser than a standard paper counterpart (almost twice as dense!), it has a higher bursting and tensile strength. Like all papers, glassine is available in various weights, so you’ll find glassine options at various quality, density, and strength levels.

Toothless: A paper’s “tooth” describes the surface feel of paper. The higher the “tooth,” the rougher the paper. Because glassine has no tooth, it is not abrasive. This feature is helpful for all products but is especially important when the material is being used to protect delicate or valuable art.

Does not shed: Standard paper can shed tiny fiber bits (rub a cloth against a shipping box, and you’ll see what I mean). Paper fibers have been pressed with glassine, leaving a smooth, glossy surface that does not shed onto the substrates it touches.

Translucent: Glassine that hasn’t been further treated or tied is translucent, allowing someone to visualize what is on the other side. While it is not clear (like plastic is), glassine is translucent enough to work well in various functions - from baked goods to art archival to packaging.

Static-free: Thin clear poly bags are notorious for producing static. The bags cling to each other, cling to products, and can quickly get all over a workspace. Not so with glassine.

Sustainability characteristics of glassine.

People often ask us, is glassine more sustainable than plastic? Is it more sustainable than other papers?

Glassine isn’t necessarily more and less eco-friendly than other materials. The better question is - can glassine replace an existing packaging material that you are using and help you achieve your sustainability goals?

Here’s are the eco characteristics that glassine has going for it:

  • It is made from wood (not fossil fuels)
  • We can make it with FSC certified paper, which is sourced from trees that are generally grown in responsible ways
  • It is curbside recyclable and very valuable input into the paper recycling stream
  • Naturally biodegradable and compostable

It is not a perfectly ecological material!

Currently, glassine is always made with entirely virgin paper.

While paper is a renewable material and can be made with responsibly grown raw inputs, it is still all virgin content.

Additionally, converting wood into glassine is resource-intensive and creates air and water pollution.

All things equal, EcoEnclose would prefer 100% recycled paper over glassine paper. However, when the functionality benefits of glassine (its clarity and smooth finish) are needed, it is an excellent choice for brands looking for plastic-free packaging.

What is glassine NOT?

Glassine (on its own) is not coated with wax, paraffin, silicone, or any other substance.

Glassine is most often confused with wax paper and parchment paper.

Parchment paper is a cellulose-based paper that also contains silicone. The silicone creates a heat resistance and non-stick surface. However, parchment paper is not water-resistant. As a result, parchment paper is great for cooking (it can be heated up to 420 degrees) but is not recyclable or compostable.

Wax paper is paper that is coated with paraffin or soybean-based wax. It is non-stick and water-resistant but is not heat resistant. Wax paper is not recyclable or compostable.

Parchment paper and wax paper are predominantly used in the food industry and are not common materials for non-food packaging.