It’s been a while since I’ve posted about “On habitats” — the series designed to help me (us) take a moment and reflect on where the fiber in our yarn comes from. Part One of this series looked at Natural Plant Fibers, Part two: Synthetic Plant Fibers took a look at tencel, bamboo and corn, and Part three finished off synthetic plant fibers with soy, rayon, and modal. This week will focus on non-plant based synthetic fibers, namely nylon, acrylic, and spandex.

Nylon is a polymer, or a plastic constructed of short repeating sections of atoms (think chain link construction) and is created by reacting two molecules with heat and pressure. This then produces a ribbon of nylon that is shredded into chips that can be used for many different types of everyday plastic.

Nylon yarn, or strands of nylon to be blended with other yarns, are created by melting these chips and drawing them through a spinneret. The length and thickness of the strands are determined by the hole size and the speed of the spinneret.

Nylon was the first created in the spring of 1930 by Julian Hill, by accident, and became a replacement for silk in wartime parachutes. Today, nylon is in almost everything, from toothbrushes and umbrellas to machine gears due to its durable nature and natural waterproofing.

While it’s in everything, nylon is not free from environmental impacts. For starters, nylon is not biodegradable, two of the largest sources of microplastic pollution are fishing nets and synthetic textile fibers that wear off during washing (now I feel a little guilty about washing my tights). The bright side to this is that nylon is also infinitely recyclable — we could probably stop producing new nylon, reuse what we’ve made and still have enough nylon for all our nylon needs.

Additionally, nylon is not suited to natural or low impact chemical dyes. This means that the process of dying nylon creates significant water pollution and the emissions from a single power plant are high. The flexibility of nylon does come with a cost.

Acrylic yarns are made from a poly compound called acryonile, which is a type of plastic. The compound is first dissolved in a solution then put through one of two spinning methods.

The first method is known as dry spinning. During dry spinning, the compound solution is run through a spinneret to dissolve the solvent (liquid) so that continuous filaments are created. These filaments can then be cut to the desired length and added to other fibers.

The second method, or wet spinning, sets the compound solution into a coagulating bath until filaments are formed. Once the filaments are formed, they are then drawn, dried and processed.

The problem with acrylic yarns is that the process used to turn the plastic into a yarn requires a large amount of fossil fuel and it releases toxic fumes into the air. Additionally, each time that acrylic yarn is washed in a standard in-home washing machine microplastics are released into the water. While you can’t see microplastics due to their size, they add up fast. An estimated 85% of man-made waste on shorelines are made up of microplastics, a substance that will take up to 200 years to fully biodegrade.

Acrylic seems to be used for a variety of reasons. For starters, they are stretchy while also being durable, machine washable, don’t shrink and are moth resistant. Many claim that they’re perfect for baby knits, but I’m not convinced. Plastic melts when it gets hot! Don’t wrap your baby in a plastic blanket!

Spandex, a lightweight fiber often used to make clothing incredibly stretchable (spandex fibers can stretch up to 500% their length! Hello crazy math!), was developed during World War II as a replacement for rubber.

The first step in creating spandex fibers is to create a pre-polymer (unlike nylon and acrylic the polymers do not exist in nature already). Compounds are mixed in a reaction vessel and then added to a solvent to make the solution thinner and easier to handle. The solution is then pumped into a spinning cell (a spinneret in the presence of heat, nitrogen and solvent gas) and converted into fibers. Once the fibers leave the cell, they are bundled together to produce the desired thickness using a compressed air device that twists the fibers together. Finally, the fibers are treated with a finishing agent to prevent them from sticking together during textile manufacturing.

As with the other synthetic fibers, the creation of spandex comes with the repercussions of toxic chemical usage and a lot of energy required to produce them. They’re also created from polyurethane, which is a known carcinogen, and are not biodegradable (which is really bad when you consider how often you need to invest in new tights, sports bras etc).

My verdict on these fibers? It’s hard to say. Specifically, because it would be hard to completely give them up. I know I benefit from the spandex in my sports bras and the socks I knit out of yarns that contain a small percentage of nylon really do hold up better than the ones that don’t (perhaps there is a way to encourage the market to use recycled nylon!). Finally, I love my fleece jackets, they’re perfect for running and keep me warm even when I’m running in the rain (if fleece wasn’t made out of acrylic this would have been the easiest to dump down the drain).

That being said, you don’t have to convince me not to use acrylic yarns, I already do my best not to use them at all because like my fleece jackets they:

• Don’t breath
• Melt when exposed to heat
• Are 100% plastic

So at least I can rest a little easy. It also helps that I try to buy my clothing second hand, so at least recycling someone else’s fleece jacket!