From the 1970s I remember something new appearing on the yarn market: Superwash Wool! It was considered a blessing. Garments knit from superwash wool were so much easier to care for – they didn’t felt, they didn’t shrink and all in all they were more durable.
For the blanket I knit for our grandson, I deliberately chose a superwash merino wool to make life easier for his parents. And now, recently, I read ‘…I have stopped purchasing superwash wools…’ in this book:
Why? I thought.
And then I came across a yarn explicitly marketed as non-superwash. Again I thought, Why? (Uh-huh, I have deep thoughts from time to time.)
Intrigued, I bought a few hand-dyed non-superwash skeins. They are now an almost finished Thús 2, that I’ll finish as soon as the weather gets cooler:
‘But’, I asked the indie dyer selling this yarn, ‘does that mean that your other yarns are superwash, even though the labels don’t say so?’ ‘Not all of them, but some of them are,’ she said. I was flabbergasted.
Apparently I’d been using superwash yarns all along without being aware of it! I’d always thought that all yarns were non-superwash, unless specifically labelled as superwash. And what’s wrong with superwash yarns anyway?
Always happy with an excuse to do some research, I dived into an online sea of opinions and information about superwash versus non-superwash wool, almost drowning in it. Here is a summary of what I found out:
Why would wool need superwash treatment at all?
Wool fibres have tiny open scales that interlock when friction is applied or when they come into contact with quickly changing water temperatures, leading to felting and shrinking. Superwash treatment can prevent that.
A controversial superwash treatment
The most commonly used method for shrink/felt-proofing wool by far is the chlorine-Hercosett process. After washing, but before spinning, the wool goes into a bath of diluted chlorine to dull the scales. And after that the scales are coated with a synthetic (polymer) resin to make them even smoother and prevent the wool from felting/shrinking. There is a lot of debate about this method:
- On the one hand: The chlorine-Hercosett method requires large quantities of water and produces an environmentally hazardous effluent. In some parts of the world this may lead to water pollution.
- On the other hand: Because of the strict waste water legislation in the EU and some other countries the effluent is treated to such an extent that only very clean water leaves the factory.
- Positive: This treatment prolongs the lifespan of items made from the wool.
- Question mark: Does the resin coating release micro pollutants when the wool is washed? Some producers say that the resin used is biodegradable and does not, but somehow I do not feel completely assured.
More environmentally friendly alternatives
- EXP, which stands for EX-Pollution, was developed by Schoeller. This method avoids pollutants altogether, but still uses extra water.
- Naturetexx Plasma, a treatment not using any water at all, but just air and electricity. The drawback is that it uses lots of electricity and there are questions about the durability of the wool treated in this way.
So, what is an environmentally conscious knitter to do?
It’s complicated – sigh! The labels don’t tell us much. They sometimes tell us that a yarn has been superwash treated, but not always. And they don’t tell us which treatment process was used. What we can do is this:
- Visit yarn manufacturers’ websites. Some of them give useful information about their production process.
- Look for yarns with the GOTS (Global Organic Textile Standard) label. Chlorine cannot be used in any stage of the production of these yarns.
- Remember that any superwash treatment makes knitted garments last longer, which is also sustainable, and may be necessary for items that need to be washed often, like baby things.
- Choose non-superwash yarns for items that do not need frequent washing. Some people say that non-superwash yarns have less saturated colours than superwash ones, but I find that hard to believe looking at these yarns from my nearest indie dyer.
- A review of the sustainable methods in imparting shrink resistance to wool fabrics
- Article about the EXP process
- Article about the Plasma technique
- Clara Parkes on shrink proofing
- A yarn producer about their superwash treatment, another one, and another one
Okay, after all that seriousness, I think we deserve few more colourful yarn-filled photos, don’t you?