The Science of Bio-Synthetic Yarn

When I was still working at my old job, I often had to field questions about the fiber content of yarns. Most of the time, this was simple, as many of them were your standard fibers like wool, cotton, cashmere, or alpaca. But there were a few that led even the most seasoned knitters to tilt their heads to the side, confused about how certain materials would end up in a skein of yarn. These were the bio-synthetics.

Some bio-synthetic fibers are fairly common, like rayon, soy, or bamboo. But there are plenty that consumers aren’t even aware exist in yarn form, especially ones that come from sources we normally think of as food.

Yes, food. I’m not talking about knitting something out of string licorice or cooked spaghetti here. What we’re going to learn about are yarns made from corn, chitin, soy, seaweed, banana, sugar cane, and milk. It may sound like some bizarre salad, but these things are the basic raw materials for many bio-synthetics.

So, how do we get from something like liquid milk or a crab shell to a skein of luxurious yarn? When cellulose and other polymers are cooked down and extruded, they begin to form fibers which can be spun into yarn. Often the bio-synthetic material is blended with another fiber, like wool, silk, or cotton, and depending on the source they all have different properties.

Chitin is derived from the pulp of crustacean shells, and is structurally similar to cellulose, which means it will blend well with other fibers and take dyes nicely. Yarn from this fiber has antibacterial properties, which means it might be a nice choice for socks or anything else that has the potential to get dirty. Of course, it’s not vegan, and there have been some posts on knitting forums saying to avoid the stuff if you have any seafood allergies.

Bamboo is a pretty popular fiber, especially in hot weather. It can be very soft and have a nice luster to it, plus it’s light and breathable, making it great for summer projects (no one wants to hold wool when it’s 90 degrees out). Since it’s plant-based, it’s vegan (unless blended with an animal fiber, of course). However, it can be a bit splitty to work with. Thanks to its popularity, it’s easy to find if you want to try it, with cheaper options from Knit Picks and Lion Brand.

Rayon, which is more of a category (that includes modal, viscose, and tencel) than an individual fiber, come from wood pulp. Undoubtedly, you are already familiar with the properties of these materials, since they’re already widely used, but let’s refresh anyway. Rayons are generally very soft and drapey, and can be found in many store-bought clothes, plus it turns up a fair bit in blended yarns. Habu Textiles makes a very interesting 100% viscose yarn, and Berroco Seduce is rayon and viscose blended with linen and silk. Rayon pops up in so many yarns that making a comprehensive list would be an article in and of itself.

Soy yarns are manufactured using the by-products from making tofu and other food items. It’s strong like silk, plus has a nice luster while maintaining breathability. I’ve personally knit with Patons SWS, which is a wool-soy blend, and liked how it combined the warmth and fluff of wool with some sheen and softness from the soy fiber.

Corn yarn is another nice, breathable fiber that shares a lot of properties with cotton and bamboo. It comes from fermented sugars in the corn, and the resulting fiber has some interesting stain-and-odor-resisting qualities, good moisture control. It’s also springy and quick-drying. Southwest Trading Company’s A-MAIZing (get it?) comes in some interesting colors.

Sugar cane yarn comes from “bagasse,” which is the stalk part of the plant that is left behind after the sugar we eat is processed out. The plant is shredded before being processed, and the resulting yarn is soft, drapey, and lustrous. Ruca by Araucania is a sugar viscose yarn that comes in a variety of solid and variegated colors.

Banana silk yarn comes from the bark of the banana tree and has properties similar to rayon. Frabjous Fibers sells one that knits up bulky and is hand or kettle dyed by women in India.

Milk protein yarn is the other non-vegan bio-synthetic, being processed from casein. This is done through a skimming technique, extrusion through a spinneret, and the addition of certain chemicals. Going from liquid to fiber isn’t a simple process by any means, but it does result in a yarn that’s shiny, silky, and soft. Anzula Milky Way is a milk protein-superwash wool blend that is lovely to the touch (though pricey). Kollage Creamy Flame is blended with cotton and is a bit more affordable if you want to try it out.

SeaCell yarn is soft and very strong, with good draping properties. It comes from the cellulose in seaweed, and is beautiful in blends. Anzula Mermaid is a stunning (though, again, pricey) blend of SeaCell and silk which is light and drapes like an absolute dream, however, they are temporarily not manufacturing it. Handmaiden Yarn sells their own Sea Silk, which is the same blend and likely has the same properties.

Many of these bio-synthetic yarn manufacturers claim that their products have health and skin benefits. This may be junk science and good marketing, however, so approach those claims with a certain skepticism. But, even if they don’t cure all of your external and internal ailments, bio-synthetics are still an interesting corner of the fiber market, and one worth exploring if you’re looking for something new and different to craft with.