What Is Fleece, and Is It a Sustainable Fabric? Environmental Impacts

Fleece is the fabric of cold days and colder nights. Is it sustainable?

Colorful fleece jackets are hanging on hangers
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Fleece is the fabric of cold days and colder nights. Associated with outdoor wear, this fabric is a soft, fluffy material that is most often made from polyester. Mittens, hats, and scarves are made from the synthetic material known as polar fleece.

As with any commonplace fabric, we want to get to the bottom of whether or not fleece is considered sustainable and how it compares to other fabrics.

History of Fleece

Fleece was originally created as an alternative to wool. In 1981, the American company Malden Mills (now Polartec) was the first to create a napped polyester material. Through a partnership with Patagonia, they would go on to produce a better-quality fabric that was lighter than wool but still performed in a manner similar to the animal-derived fiber.

A decade later, another collaboration between Polartec and Patagonia emerged; this time the focus was using recycled plastic bottles to create fleece. The first fabric was green, the color of the recycled bottles. Today, brands are taking the extra steps to bleach or dye recycled polyester fibers before putting them on the market. There is now an array of colors available for fleece materials made from post-consumer waste.

How Fleece Is Made

While fleece is generally made from polyester, technically speaking it can be made from just about any type of fiber.

Similar to velvet, the main characteristic of fleece is the napped pile fabric. To create the nap, or raised surface, Malden Mills used a cylindrical wire brush to break the loops produced when weaving. This also pushed the fibers upward. This method, however, caused the fabric to pill, producing small balls of fiber on the surface of the fabric.

To solve the pilling problem, the material was essentially "shaven," which allows for a softer-feeling textile that retains its quality much longer. This same basic technique is used to create fleece today.

Fleece Made From Virgin Polyester

Polyethylene terephthalate chips are the beginning of the fiber-making process. These chips are melted down and then forced through a disk with very fine holes called a spinneret.

As the melted chips come out of the holes, they begin to cool and harden into fibers. The fibers are then spun onto a heated spool into large bundles called tows, which are then stretched to make longer and stronger fibers. After stretching, it is put through a crimping machine to give it a crinkled texture and then dried. At this point, the fibers are cut to a few inches to resemble wool fibers.

The fibers are then ready to be made into yarn. The crimped, cut tow are put through a carding machine which forms ropes of fiber. These strands are then sent through a spinning machine, which creates much finer strands and spins them into spools of thread. After being dyed, the threads are knitted into cloth using a knitting machine. From there, pile is created by running the cloth through a napping machine. Finally, a shearing machine will cut down the raised surface creating the fleece.

Recycled Fleece

The recycled PET used to make fleece comes from recycled plastic bottles. The post-consumer waste is cleaned and then sterilized. After drying, the bottles are crushed into tiny chips of plastic that are washed again. Lighter colors are bleached, and the green bottles are kept green to be later dyed into darker colors. The same process that takes place with virgin PET is then followed: The chips are melted down and turned into thread.

Fleece vs. Cotton

The biggest difference between fleece and cotton is that one is composed of synthetic fibers. Fleece is designed to mimic wool fleece and retain its hydrophobic and thermal insulating properties, while cotton is more natural and more versatile. It is not only a type of material but also a fiber that can be woven or knitted into any type of textile. Cotton fibers can even be used to create fleece.

Although cotton has its share of environmental detriments, it is widely seen as more sustainable than a traditional fleece. Because the polyester that makes up fleece is synthetic, it can take decades to break down, whereas cotton biodegrades at a significantly faster rate. The exact rate of decomposition depends on the conditions the fabric is in and whether or not it's 100% cotton.

Environmental Impacts

Fleece made from polyester is often a high-impact fabric. For starters, polyester is made from petroleum, a fossil fuel and finite resource. The processing of polyester is a known drain on energy and water and is also heavily laden with harmful chemicals.

The dyeing process for synthetic fabrics also creates environmental impacts. Not only does the process use an exorbitant amount of water, but it also discharges wastewater that contains unexpended dyes and chemical surfactants, which are harmful to aquatic life.

Though the polyester used in fleece isn't biodegradable, it does break down. However, that process leaves behind tiny pieces of plastics known as microplastics. This is not just a problem when fabrics end up in landfills, but also when fleece garments are washed. Consumer use, specifically laundering garments, has the highest environmental impact within a garment's life cycle. It is believed that approximately 1,174 milligrams of microfibers are released when washing a synthetic jacket.

Recycled fleece has less of an impact. Recycled polyester uses 85% less energy. Currently, only 5% of PET is recycled. Because polyester is the number one fiber used in textiles, increasing this percentage will have a significant impact when it comes to reducing energy and water usage.

The Future of Fleece

As with many things, brands are searching for ways to lessen their environmental impact. In fact, Polartec is leading the way with a new initiative to make their line of textiles 100% recycled and biodegradable.

Fleece is also being made from more natural materials, such as cotton and hemp. These continue to have the same properties as technical fleece and wool with less harmful effects. With more attention being paid to circular economies, it is more likely that plant-based and recycled materials will be used to make fleece.

However, because only 14% of apparel is made from recycled fibers, there is still quite a way to go.

View Article Sources
  1. "Polyester is a Synthetic, Non-Renewable Fiber, with Some Surprising Redeemable Qualities." Natural Resources Defense Council.

  2. Yuan, C.L., et al. "Study on Characteristics and Harm of Surfactants." Journal of Chemical and Pharmaceutical Research, vol. 6, no. 7, 2014, pp. 233-2237.

  3. Hicks, Andrea L. and Thomas L. Theis. "A Comparative Life Cycle Assessment of Commercially Available Silver-Enabled Polyester Textiles." International Journal of Life Cycle Assessment, vol. 22, 2017, pp. 256-265., doi:10.1007/s11367-016-1145-2

  4. Hartline, N.L., et al. "Microfiber Masses Recovered from Conventional Machine Washing of New or Aged Garments." Environmental Science and Technology, vol. 50, no. 21, pp. 11532-11538., doi:10.1021/acs.est.6b03045

  5. "2025 Recycled Polyester Challenge." Textile Exchange.