Superwash versus Non-Superwash

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Skeins of gray yarn hanging on wooden clothespins.

Superwash skein left, non-Superwash skein right.

Superwash and non-Superwash yarns, what’s the difference? After all, aren’t they both wool? In my view as a knitter and a natural dyer, they are related in the way a horse, and the Emerald City’s Horse of a Different Color would be!

To understand, let’s look at the horse first, or in our case the raw wool! Sheep wool is made of natural fibrous proteins from the keratin group. The keratin is what gives yarn its flexibility, elasticity, resilience and memory. Each “hair” has a complex physical structure, and is made up of overlapping minuscule scales. The scales help repel dirt and allow the fibers to felt. In the case of some non-Superwash fibers, felting does not occur, as in down breeds. In their natural state, the fibers are coated with a waxy coat of lanolin which serves as a water repellent. During wool processing, the lanolin is removed.

Now, let’s look at the Horse of a Different Color, the Superwash. The most common treatment used to transform a yarn into “Superwash” is the Chlorine-Hercosett process. To etch the scales we talked about earlier, the fiber is chlorinated with either chlorine gas or a chlorine solution, followed by the application of a plastic resin to coat the fibers. The result is a yarn you can wash in the washing machine that will not felt.

Before I discuss the difference between the two types of yarn from a dyeing and a knitting perspective, I want to point out some of the negative environmental impacts of the Chlorine-Hercosett process. This process is not sustainable, it uses hazardous chemicals, and creates toxic waste. It uses more water and energy than traditionally processed wools, and the yarns, after they are transformed into garments or household products, shed microplastics during washing.

Because of the negative environmental impacts of the traditional Chlorine-Hercosett process, new processes have been developed to improve the washability of wool, and decrease felting. Among them, to name only a few, are the EXP process which does not use chlorine and instead uses natural salts as oxidizing agents, and the Naturetexx Plasma Process which uses air and electricity.

Now that I have said that, and that I am sure you are looking sadly at all the beautiful skeins of Superwash in your stash, you are wondering what to do. My answer is: use them! The resources and energy that were used to produce them have already been expended, and not using them would be a waste.

So how do the horse and the Horse of a Different Color compare? The two skeins below and their samples were knitted from 100% Merino fingering yarn, one non-Superwash, the other Superwash, with both skeins weighing 20g each.

Body in the skein

Two photos of gray yarn, with the bottom one curling over the edge of a table.

Non-Superwash top, Superwash bottom.

The difference in body between the two skeins is very apparent in the pictures below. The non-superwash skein which appears first has body, whereas the superwash clearly has not retained its natural structure. The yarn is flatter, and denser.

Drape

Four gray swatches of knitting.

No-Superwash top, Superwash bottom.

The difference in body translates into the drape. I knitted two identical swatches. The Superwash Merino drapes more than the non-Superwash, but is also more shapeless.

Color

Small balls of gray yarn.

This is where my experience as a hand-dyer comes in. Superwash yarns absorb color more readily than non-Superwash. Non-Superwash yarns appear more subtle, while Superwash yarns are deeply saturated. Even with natural dyes, my dyes of choice, the color difference is striking. Both yarns were identically dyed together using sequoia. In addition, the absorption of color is faster in a Superwash skein than it is in a non-Superwash skein.

Shine

The difference in color is only accentuated by the difference in light reflection. A Superwash yarn is smooth with a slight sheen, while a non-Superwash yarn is matte with a soft glow.

Elasticity/Memory

Gray yarn swatches hanging on wooden clothespins.

Superwash skein left, non-Superwash right.

Superwash yarns lose their elasticity, and memory. The absence of scales, means the fibers and stitches are sitting next to each other but are not interlocked, so they tend to stretch more readily. This would be fine for a shawl, but less attractive for a sweater. The tendency to stretch is visible when the samples are wet.

Gauge

Folded swatches and twisted hanks of gray yarn.

Superwash left, non-Superwash right.

With an equal number of stitches cast on in these samples, the Superwash swatch is wider and longer than the non-Superwash swatch. The stitches in the non-Superwash swatch are closely connected to each other, while the stitches in the Superwash swatch remain clearly separate, with minute gaps. This will have an impact on the warmth of the knitted garment, with non-Superwash yarn being significantly warmer. The Superwash swatch is flatter. Textured stitches will appear flat in the Superwash Merino, and round and plump in the non-Superwash Merino.

Softness

Both are soft, though in a slightly different way. In the case of Merino yarns, Superwash feels sleek and non-Superwash feels pillow-y.

Water

Water sitting on gray stockinette swatches.

Non-Superwash top, Superwash bottom.

The Superwash yarn will absorb water faster as opposed to the non-Superwash yarn which will repel the water. A non-Superwash garment will allow you to stay warmer even when wet.

As a natural dyer, a knitter and a spinner, I prefer non-Superwash fibers. Each breed-specific fiber has unique properties that make one fiber or another ideal for a particular project. The same way a Superwash Merino is drastically different from a non-Superwash Merino, Merino fiber is drastically different from let’s say Suffolk or Wensleydale. And as I hinted earlier in my post, some fibers felt and some do not. There is a perfect natural fiber for any project! This could be the subject of a whole new post, but for now, I hope you will look at your stash a little differently, and that you will explore the possibilities in using non-Superwash fibers.

References

It’s Not You, It’s the Yarn: Superwash Edition by Jillian Moreno

Why Not Superwash Yarns? from Knitting the Natural Way

Why Is Superwash Yarn Not Sustainable? by Making Stories

Are There Sustainable Superwash Options? by Making Stories

The Structure of Wool