Non-Superwash and Superwash Yarns

One of the questions that we get asked most often is if our yarns are superwash-treated. The short answer is: Almost all of them are not – except for Exmoor Sock, all our yarns are non-superwash.

Why do we love non-superwash yarns?

Wool is one of the most magical materials out there! In our non-superwash yarns and fibre tops, we work with the scoured, carded and combed fibres of the different sheep breeds we blend together.

They're not chemically treated in any way, and so the resulting non-superwash yarn holds all of those properties that make us love wool: 

1. It's warm: Non-superwash yarn looks a little like a human hair under a microscope – lots of tiny scales that overlap each other. These scales help trap the air in the yarn and fabric made out of that yarn, and the more air is trapped, the warmer the fabric!
2. It bounces back into shape: Another advantage of those scales is that they help the fabric bounce back into its original shape after it has been stretched. The scales cling to one another and when they're moved apart - say, when you pull a jumper over your head - they want to get back to one another. This is why wool knits can be blocked back into shape over and over again!
3. It doesn't smell: If you've knit with non-superwash yarn, you might have noticed that the knits don't really smell, even if you've worn them a ton. This is because wool wicks away moisture from your skin and at the same time breaks down skin oils - both of which help against those nasty smells you often get with synthetics! 
4. It's great for colourwork and texture: Due to its elasticity (the "bouncing back in shape") and the scales clinging to each other, non-superwash yarns work wonders in colourwork and textured patterns.

Now on to the (pretty obvious) one point that makes non-superwash yarns a teeny bit more involved to work with: Items knitted from them should be washed by hand, not in the washing machine. The lovely scales we talked about also like to felt, which is much more likely in a washing machine (even on a wool cycle) than when you hand wash your knits.

The good news is that due to the moisture-wicking and oil-repelling properties of wool, your non-superwash knits actually don't need a lot of washing! Usually, a good rinse with wool wash after a full autumn and winter season is enough – no need to wash them more than that. If you've caught a few smells in a jumper - say, from cooking in it, or a bonfire - simply hang it outside for a couple of days and it's as good as new.

After a little dive into the benefits of non-superwash wool, let's take a look at the alternative: superwash treated yarns. What is actually behind the superwash process? How does it work and what difference does it make to a yarn?

What is superwash?

Superwash yarn and fibre (yes, there's also superwash fibre for the spinners out there!) has undergone an additional processing step to make it shrink-resistant and therefore machine-washable. For our Exmoor Sock, the Exmoor Blueface and Falklands Corriedale tops we use are superwash-treated before we receive them. We blend these fibres with some non-superwash Zwartbles and Nylon, and then spin the resulting tops into Exmoor Sock yarn.

So, why does wool shrink? It shrinks because it felts: The tiny scales that contribute to so much of the awesomeness of wool (they trap air to keep you warm and they increase the surface area of the fibre so that it can hold more water) have a strong tendency to link arms when rubbed against each other. As they hold on to each other, the fibre becomes smaller and smaller, denser and denser - it felts.

So to make yarn machine-washable, you have to get rid of the scales. There are - generally - two ways to do this: You can either strip the scales off the fibre, or you can coat it in something to flatten the scales. 

The most common superwash process - used for approx. 75% of all superwash-treated wool - is the Chlorine-Hercosett process which combines both techniques. As a first step, the fibre is chlorinated, i.e. treated with chlorine gas or a chlorine solution, to get rid of the natural 18-MEA (18-methyl eicosanoic acid, a fatty acid that helps to repel water) coating the fibre and to etch away the edges of the scales. In the second step, a polyamide-epichlorohydrin resin - more commonly known as Hercosett 125 - is applied to the fibre.

The removal of 18-MEA and the edges of the scales helps with the distribution of the resin; the application of the resin creates the 'superwash' coat that helps prevent felting and shrinkage. This is the process that is used on the Exmoor Blueface and Falklands Corriedale tops before we receive them.

What are the properties of superwash yarn?

The yarn that comes out of this process has a few distinct advantages:

1. It's machine-washable: Because the yarn has gone through the superwash process, it can be washed in the machine without fear of shrinking or felting. Be aware though that this still means you need to use a wool cycle in the washing machine! If you use a higher spinning cycle or higher temperatures, even superwash yarn can felt.

2. It takes dye beautifully: Superwash yarns can absorb more dye than non-superwash yarns due to the de-scaling and smooth resin-coated surface. This means that the colours achieve a lot of depth and are really vibrant.

3. It's soft: The removal of the scales and coating of the fibre in resin results in a much smoother and therefore softer surface than most non-superwash yarns can offer.

It also has a range of disadvantages:

1. It's not as elastic: If you've knit a sweater in superwash yarn, you will have noticed that it's not easy to coax it back into shape when it's been washed. This is because the yarn itself loses much of its elasticity - its 'springiness', if you will, it's ability to hold and spring back into the shape you intended it to - as the individual fibres are not able to cling to each other anymore.

2. It's not as warm: The scales on untreated wool fibre trap air, and air equals warmth. They are the reason your woollens keep you warm even on the coldest days, and when you remove them, you also remove the yarn's potential to warm you.

3. It doesn't repel water as well: If you've gotten into a rain shower with only a (non-superwash) sweater on, you might have noticed that you don't get as wet as fast, right? Wool has natural water-repellent properties, and as you remove both the chemical and physical ones (hello 18-MEA from up above! hello scales!) during the superwash process, a superwash yarn won't repel water as well as an untreated one.

We love our non-superwash yarns a lot, and also have a very soft spot for Exmoor Sock. For socks, a woolly item that you would wash a lot more often than, say, a sweater, we do think that a superwash-treated yarn has its place!