null
What is Glassine?

What is Glassine?

Sep 14th 2020

We are thrilled to introduce our latest offering: Glassine Bags for inner or wholesale packaging. A paper-based alternative to the clear poly bag. But...what is glassine? Read on!

Glassine is often used for:

glassine bag, glassine merchandise bag

Bakery and snack bags

Merchandising

Archival

Art protection

And now...product and apparel protection

What is glassine and how is it made?

Glassine is a 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 normal 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 special process called supercalendering.

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

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

This isn’t just basic “pressing,” as the process actually 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.

super calender machine for glassine

Source: Valmet

supercalendering glassine

Sustainability Characteristics of Glassine

  • Made with paper (not fossil fuels)
  • Often (such as ours) made with FSC certified paper
  • Curbside recyclable
  • Naturally biodegradable
  • Downsides: Currently, always made with fully virgin paper. While paper is a renewable and responsibly grown raw material, the process of converting wood into glassine is resource intensive and creates air and water pollution.

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 surroundings.

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

Durable and stronger than standard paper of the same weight: Because glassine is so much 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 a range of weights, so you’ll find glassine options in a variety of different levels of quality, density and strength.

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 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 bits of fiber onto things it comes into contact with (rub a cloth against a shipping box and you’ll see what I mean). With glassine, paper fibers have been pressed, 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 get a visual of what is on the other side. While it is not perfectly clear (like plastic is), glassine is translucent enough to work well in a variety of 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 easily get all over a workspace. Not so with glassine.

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. Parchment paper is not water resistant. 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.