Choosing Sustainable Fabrics

It's a heatwave! What should I wear?

We've all been there. You get dressed, step into the scorching heat, and realize that you've put on the wrong outfit. Searching for the right outfit begins with the right fabric. Some materials trap heat and sweat, while others breathe and keep you dry. Knowing the difference can mean the difference between comfort and misery. This guide breaks down the best (and worst) fabrics for summer, with sustainability in mind.

Natural Fabrics

Natural fabrics are great thermoregulators, meaning they keep you cool when you're hot, and trap heat when you're cool (ta-da!). That said, some are better for hot weather than others.

• Silk: Silk is widely recognized as both luxurious and fussy. Made from the cocoon of a silkworm, in most production processes, the cocoon is boiled so the moth never emerges. It can take an estimated 1,000-2,000 silkworms to make one silk shirt through this not-so-humane process.
• Cotton: Cotton is one of the most popular fabrics in the world, and for good reason. However, it tends to retain moisture when wet. Sweat a lot? Good luck! If you choose cotton, try going with a slub cotton, which is textured for enhanced breathability. Keep in mind that cotton production requires major chemical inputs and an immense amount of water.
• Wool: An unexpected summer contender! Many associate wool with warmth, but it's a strong all-around thermoregulator. Wool also has great odor-controlling antibacterial properties, which will keep you cool for other reasons. A nice lightweight merino is more breathable than cotton and will dry faster--but is wool sustainable? This is a topic of debate.

• (BETTER) Linen: Linen is a magical fabric woven from the flax plant that is scientifically proven to be cooler than both cotton and silk. It is also considered more sustainable. Linen absorbs and releases moisture quickly. Its texture is very stiff, which reduces points of contact with the body. Both these factors keep you cool and dry. Unfortunately, stiffness also makes linen prone to its infamous wrinkles.
• (BEST) Hemp: Special shoutout to hemp, which has very similar properties to linen (minus the wrinkles) but is considered more durable and sustainable. Unfortunately, hemp garments are often hard to find, since hemp was classified as a controlled substance in the US until 2018, hampering innovations in growing and processing.

Tips:

EMBRACE THE LINEN WRINKLES! As always, try shopping secondhand first, for any garment.

Semi-Synthetic Fabrics

Rayon, viscose, Lyocell, Modal, TENCEL? What gives? Rayon is the umbrella term for these semi-synthetic fabrics, which are made from chemically transforming cellulose derived from wood or bamboo pulp. Viscose is a type of rayon, but is so common that the two terms are often used interchangeably. Rayon is considered a silk alternative because of its light weight, breathability, and drape.

• Rayon and viscose: 30% of the pulp used in generic rayon is from endangered or ancient forests. Rayon is also produced through a highly toxic process--so toxic, in fact, that in WWII, the Nazis forced political prisoners to work in rayon factories. Chemicals used in rayon production cause acute health problems--including heart disease, nerve damage, and impaired motor function--and they often end up in the environment. Today, rayon and viscose production have largely moved to countries lacking labor and environmental protections.
• Modal and lyocell: Since rayon's invention, innovations have led to more sustainable and humane production. Modal and lyocell are considered "second-generation" rayons, with modal derived from beech and lyocell from fast-growing trees like eucalyptus. These fabrics are produced in a closed-loop system, meaning that solvents are monitored, treated, and re-used, making the process safer. On top of that, lyocell production uses non-toxic chemicals.
• ECOVERO and (BEST) TENCEL: ECOVERO Viscose and TENCEL Modal and Lyocell are brand-name rayons trademarked by Lenzing, a company that regulates its supply chain. For example, Lenzing sources its pulp only from PEFC or FSC certified forests, and it also ensures its closed-loop production for modal and lyocell recovers 99.8% of solvents.

Tips:

When done well, rayon can be more sustainable and humane than some natural fabrics. Confusing terms make rayon prone to greenwashing, like labelling fabrics as "bamboo viscose". Make no mistake, generic rayon and viscose are bad and should be avoided. Look for Lenzing trademarks--of these, TENCEL Lyocell is considered the most sustainable. One negative for rayon is that its structure weakens when wet. Be sure to wash on a cold, delicate cycle, or place items in a wash bag, and air dry to prolong the life of these garments.

Synthetic Fabrics

Synthetic fabrics are made from fossil fuels. Acrylic, nylon (a type of polyamide), polyester, spandex (aka elastane, Lycra) were all popularized and/or invented by DuPont. Synthetics, unless woven through special techniques, suffocate the body (imagine wearing a plastic bag).

Why is activewear made from synthetics? Synthetics are low-maintenance, have large amounts of stretch, and are moisture-wicking. Since these fabrics are literally made from oil, they are both hydrophobic and lipophilic--meaning they transfer water but trap oils, both of which are found in sweat. Synthetics may keep you dry, but you've probably noticed over time that they begin to smell.

Synthetics are resistant to wrinkles and hold textures (e.g., pleating) and color really well.

Tips

Fast fashion uses a lot of polyester because it's cheap and intended to be thrown away. Once in a landfill, these items will never degrade. Still, depending on the application, synthetics can be hard to beat. There are huge differences in quality, since many companies develop innovative technical fabrics using synthetic fibers. Sometimes, synthetics are also blended with natural fibers to improve their stretch and functionality--although, equally or more common, synthetics are blended to cut corners. Regardless of innovation or cost, these fabrics shed microplastics each time they're washed. Consider the use, care, and lifespan of the garment carefully before buying.

Final tip

Keep in mind that these are just considerations for fabric. What companies do to transform these fabrics into garments has its own social and environmental impacts. Consider researching brands before purchase.