The Truth About Superwash

If you’re involved in fiber arts, chances are that you’ve heard of superwash yarn. When I first started knitting I bought a decent amount of superwash yarn without ever learning a single thing about it, except that it was machine washable. During my time working at Echoview Fiber Mill, I started to learn more about how wool goes from raw fiber to beautiful yarn and finally got around to learning about superwash yarns.

Some of my handspun, non-superwash yarn

In short, superwash yarn is a yarn that has gone through a series of processes to prevent the wool from felting when you wash it. To understand this a little better, I first want to talk about the structure of wool itself. Each strand of wool is covered in microscopic scales. These scales give the wool its insulating properties by trapping warm air and holding it against the body of the wearer. The wool’s waxy lanolin surface also gives it water-repellent properties which make it a great choice for outdoor wear. In addition to all these benefits, the overlapping scales also give wool its ability to felt. When wool felts, the scales on each fiber link together and are pulled closer, resulting in shrinkage/felting.

To create superwash yarn, the wool’s scales have to be taken care of. To accomplish this, the wool is put through two separate processes, known as the Chlorine-Hercosett process. First, it is treated with chlorine gas or a chlorine solution to remove the natural fatty acid that helps to repel water. This removes the edges of the scales and smooths the fiber to prepare it for the next step. Then, the fibers are coated with a type of plastic resin to ensure it stays smooth and flat, thus preventing the felting process and making it feel soft and silky to the touch.

So basically, superwash yarn is just regular yarn that’s been coated in plastic and as a result, no longer has most of its original properties. However, it does have some new properties, including the ability to hold dyes much easier than non-superwash yarn. This makes it a favorite of many indie dyers and bright-color enthusiasts. So what’s the drawback? Turns out, there’s a couple.

First off, superwash yarn releases microplastics when you wash it, just like all your polyester and synthetic clothing. These microplastics come from the resin coating on top of the fibers, which degrades over time and with each wash.

The wool loses its elastic and water-repellent properties when it goes through the superwash process, meaning it can no longer do that cool trick where it absorbs up to 30% of its weight in water without feeling wet. Additionally, the harsh chemicals used can be harmful to both the people handling them and the environment. The wastewater from superwash yarn is highly toxic, and it requires more water than non-superwash yarn to create.

Finally, superwash wool is not considered biodegradable. Unlike its non-superwash counterparts which can completely biodegrade into the soil in as little as a year, the plastic coating prevents the fiber from breaking down naturally. Where natural wool will actually benefit the soil as it decomposes, superwash wool will do the opposite.

It was after learning this information that I made the decision to leave superwash yarn behind me. I do still have superwash yarn in my stash that I’ll make use of, but I don’t have any plans to buy more in the future. That said, I think it is essential to use what we already have, while also being aware of what we consume when we make new purchases. Informed consumption is always better than ignorance.