On habitats: Part 3 Synthetic Plant Fibers Continued

The “On habitats” series is 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. We’ll finish off synthetic plant fibers this week with soy, rayon, and modal.

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https://pixabay.com/photos/soya-beans-soy-bean-legume-green-83087/

Soy: According to Interweave, the first time soy was used as a textile was in the 1930s, when Henry Ford produced car-seat upholstery by blending soybean and sheep’s wool. Soybeans have a high protein content and are currently being produced in large quantities by the United States and China.

There are five main steps to creating soybean fiber, the first being the extraction of oil. Soybeans are cleaned, cracked, decorticated and dehulled before being conditioned and steeped in hexane. The hexane solution collects the oil, which can be extracted and reused. The soybean is then passed through a steam pipe to be rinsed of the solvent.

Next, the soybean is soaked in a 1% sodium sulfite solution for around an hour then filtered. This results in a creamy-white powder that is then dissolved into an alkaline solution. This solution is then allowed to age until it develops the proper consistency for spinning. The fiber is then formed by wet spinning or forcing the spinning solution through a spinneret.

Finally, the fibers are treated to baths that help it develop stretching and hardening properties. From here, the fiber can be blended and dyed.

This process doesn’t appear too bad, until you begin to look into the beans themselves. According to the World Wildlife Foundation, the soybean industry is causing widespread deforestation and displacement. Many are calling for transparent land use and an increase in proper safeguards, but until those come to pass this may not be the best yarn for an environmentally focused individual.

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Rayon: Rayon has an interesting history as an alternative to silk starting in the 1860s when the French silk industry was threatened by a disease affecting the silkworm. In 1885, Count Hilaire de Chardonnet patented the first successful process of creating a silk-like fiber from cellulose and is considered the father of rayon (despite more cost-effective ways of being created nowadays).

The major sources of the cellulose used for creating rayon include pine, spruce, hemlock, and cotton linters (residue fibers which clung to cotton seeds after the ginning process).  Regardless of whether wood pulp or cotton linters are used, the materials must be processed to extract/purify the cellulose. This results in sheets that are steeped in sodium hydroxide, dried, shredded into crumbs and aged in metal containers for 2-3 days.

Next, the crumbs are combined and churned with liquid carbon disulfide and then bathed in sodium hydroxide again. The honey-like solution (look and feel) then has any dyes or delusterants added before being filtered and stored to age (4-5 days).

After aging, the solution is forced through a spinneret and into an acid bath. Once bathed in acid, the fiber can be spun into yarn.

Unfortunately, the chemical by-products of rayon have received a lot of attention as they generate a lot of water and air emissions (the worst being zinc and hydrogen sulfide). Producers are currently trying different techniques to reduce pollution, and as the demand for rayon grows so does the demand for new technologies that make rayon better and cheaper.

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https://pixabay.com/photos/beech-tree-forest-late-summer-472095/

Modal: Modal comes from pure beech tree chips and is more or less a variety of rayon. The main difference between modal and rayon is that rayon can be made of variety or materials, while modal is only made from beech trees.

In other words, modal is made using the same process as rayon and has the same concerns. That being said, like rayon steps are being taken to make the process better and cleaner.

Main Takeaways: I think the main thing I’ve taken away from my readings on synthetic fibers is that there is no way to make them perfect. Even if the process to make the fiber is sustainable, the farming technique often isn’t (although the same can be said about cotton, which is not synthetic). All in all, I’m not sure there are many changes that I will make to my knitting — as I work mostly with animal fibers — but the curiosity around using bamboo yarn is no longer there. As this project continues, it will be interesting to learn about how chemicals are sneaking their way into my knitting. I may end up breaking my spinning wheel back out and going straight to the sheep! Or at least upping my yarn snobbery to organic yarns, depending on what I learn about man-made synthetics and animal fibers.

On habitats: Part 2 — Synthetic Plant Fibers

Last week I started the “On habitats” series to take a moment and reflect on where the fiber in our yarn comes from. Part One of this series looked at Natural Plant Fibers, which brings us to part two: Synthetic Plant Fibers. These include tencel, bamboo, corn, soy, rayon, and modal. In the interest of keeping these posts readable, I’m going to focus on tencel, bamboo, and corn this week.

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https://pixabay.com/photos/wood-tree-trunks-hardwood-logging-647597/

Tencel (Lyocell): Tencel is derived from the cellulose of hardwood trees. The trees are logged and trucked to a mill where they are cut, debarked and fed to a chipper. The hardwood chips are then turned into a pulp through the assistance of chemical digesters, which is then washed (and sometimes bleached). After the pulp is washed, it’s layed out in a large sheet and left to dry. Once dry, the sheets are rolled onto a large spool.

Next, spools are unrolled and broken into one-inch squares so that they can be loaded into a heated pressurized vessel filled with amine oxide. After a short time in this solvent, the cellulose dissolves into a clear solution and is pumped through a filter to ensure that all of the chips have been dissolved. From here, fibers are pumped through a spinneret, which leads to the creation of long strands of fiber. These strands of fiber are then immersed in a diluted solution of amine oxide (this sets the strands) and washed in demineralized water. Fibers are then lubricated (detangled), allowed to dry, run through a crimper and then carded. Once carded, they are ready to be spun.

The amine oxide solvent is non-toxic and is almost completely recycled during manufacturing, so it is not released into the environment. Additionally, the principal ingredient in this yarn is obtained by managed tree farms (no deforestation), the process uses less water and energy when compared to other manmade fibers and tencel (lyocell) is naturally biodegradable.

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https://pixabay.com/photos/bamboo-forest-nature-green-plant-828703/

Bamboo: There are two methods that can be used to get bamboo fiber: mechanical and chemical. The mechanical method involves crushing the plants into a mush and using natural enzymes to break it down before spinning it into yarn. This method is labor-intensive (expensive) and the fiber produced is not very soft.

The chemical method, a “chemical cocktail”,  contains primarily sodium hydroxide and carbon disulfide — both are known to be bad for human health and are harmful to aquatic life when released into the water supply — which produces a very soft fiber (ie the fiber used to make bamboo underwear). While companies claim this a minute part of the process, a factory producing a lot of bamboo fiber/fabric will expose their workers and the environment.

Although Bamboo itself is a sustainable resource, there is a lack of transparency and true sustainability — the soil association has not certified bamboo at this time. In addition to the process of turning bamboo into a fiber, there are concerns around it becoming a mono-crop grown only in China. This is leading to a decrease in biodiversity and an increase in pests (more pesticide needs to be used).

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https://pixabay.com/photos/corn-cornfield-corn-on-the-cob-4457379/

Corn: Corn is grown worldwide and used for food and fuel, leaving behind the husks as farm waste. These husks contain a fiber called lignocellulose which is soft and strong. Lignocellulose is separated from the husk via a patented biochemical process. This biochemical process contains common non-toxic chemicals (acetic acid, sodium chloride, sodium hydroxide, surfactants, and softeners) and is combined with water in a rotator for about a half-hour. The clumps of coarse fibers are then washed (with water) and dried before another biochemical treatment is applied to reduce the diameter of the fiber strands. Finally, the fibers are bleached, dyed and spun into yarn.

The downside? A lot of corn is genetically modified, which unfortunately means that something in the pollen is interfering with the monarch butterfly’s breeding cycle. Interesting. Essentially, while the corn fiber itself is not terrible for the environment, there are a lot of aspects (mono crop, etc) of the farming process that is.

Main Takeaways: I poked around and there isn’t a lot of corn yarn on the market yet, it looks like this could be a growing trend if the demand for the fiber increases. In terms of tencel; I don’t mind it in blends, but have not worked with a pure tencel fiber before. That being said, it’s nice to know that even though the fiber is manmade from a tree (which is a little mind-blowing) the process is both sustainable and eco-friendly. As for bamboo… I think I’m going to have to pay attention to what happens in the industry and abstain from using bamboo yarns for a little while. While I enjoy the way bamboo takes dye, I find it hard to support an industry that doesn’t have a problem exposing their employees to harsh conditions.

Stay tuned for synthetic plant fibers part two (soy, rayon, modal, and ramie), coming next week!

On habitats: Part 1 – Natural Plant Fibers

A little while ago, my partner and I grabbed ice cream from a place in town. As someone who’s very intolerant (allergic? I have gotten hives before) to Dairy, we always ask what their Dairy-free options are. This particular outing, we were met with an enthusiastic description of how they always make two flavors completely vegan (a term I am both excited and hesitant about). My partner then asked the ice cream scooper if there was Palm Oil in the ice cream as a milk substitute and he reluctantly replied: “I’m not sure”.

Why the reluctant answer? Palm oil has a bad reputation because it has been and continues to be a major driver in the deforestation of rainforests. According to the WWF, Palm oil can be produced sustainably and the Round Table of Sustainable Palm Oil (RSPO) has taken steps to create guidelines and regulations. Essentially, the ice cream scooper new that while the vegetable oil has some health benefits, it also comes with a lot of ethical concerns.

As we left the ice cream shop, my partner and I discussed what it means to be vegan and want to protect the environment if most of your alternatives are just as bad for it. As we finished our ice creams, I began thinking about Vegan knitters and their desire to work with non-animal fibers. Thus this multi-part series was born. We’ll start with plant fibers, move towards animal fibers and end with synthetic fibers. Important note: I am not vegan; the goal of this project is to take a look at what is environmentally sustainable and what isn’t so that we can all make informed decisions. 

Part One: Natural Plant-Based Fibers 

The most common plants used to create plant-based fibers include: abaca, bamboo, coir, cotton, flax, hemp, jute, kapok, ramie and sisal. In knitting, the list of plant-based fibers used to create yarn typically focuses on bamboo, hemp, linen, cotton, rayon, corn and soy. In other words, you can create fabric from a lot of different plants.

This week, we’re going to specifically focus on naturally occurring plant-based fibers: Linen, Hemp, and Cotton.

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Linen: Linen fiber is taken from just behind the bark of the flax plant and retrieved when the woody stem and the inner pith (or pectin) is rotted away. This process can be completed one of two ways: the stems are submerged in stagnant pools/running streams and the workers must wait for the rotting (about 2 weeks) or the stems are placed in a solution of either alkali or oxalic acid before being pressurized and boiled. Once the fibers are removed from the stems, the fibers are passed through machines which combine them into roving and then spun.

The greatest concern of creating linen yarn comes from the chemicals used in the rotting or retting process. Before chemicals can be released into water supplies, they must be neutralized. The plant remains themselves are typically ok unless they become impregnated with a lot of chemical during the retting process.

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Hemp: Much like Linen, Hemp must be retted from four to six weeks in order to loosen the fibers. During this process, the stalks typically lay in the field, allowing nutrients to return to the soil as the leaves decompress. The fiber is then cleaned and carded before being spun.

Unlike Linen, Hemp is not being retted using chemical baths. Additionally, the harvested hemp is not burned. This means that each part of the plant is used, saved or recycled, making Hemp sustainable.

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https://pixabay.com/photos/grass-cottongrass-cotton-flower-2295888/

Cotton: Cotton is the most flexible of plant fibers and is ready to be spun once washed, carded and combed. As long as your cotton is coming from an organic farm, it is sustainable.

Main Take-aways: As noted previously, I am not vegan and therefore not technically limited to any specific fibers. In other words, I admit that I do not typically work with 100% cotton, linen or hemp yarns. That being said, armed with the knowledge that I know now, I may reach for hemp instead of linen now that I know linen is often retted in a bath of chemicals. My relationship with cotton feels very much the same — it hurts my hands so I don’t rush to work with it.