I have recently been thinking about superwash and whether it’s an environmentally safe treatment for yarn.
I contacted my main yarn supplier and asked the question, and this is what they told me….
“Superwash is a treatment applied to wool fibres that makes them more resistant to shrinking and changes the dye absorbability. In the 80’s superwash treatment got a bad rap because in some countries the effluent was not recycled. This has, however, changed dramatically as the EU enforced very strict laws and any by-products must be removed from the water before it is discharged into the water systems. The mill we get our merino processed is accredited with the EU Flower and OEKO-TEX 100 and runs a state-of-the-art effluent treatment plant. This now means that the water is recycled and when it is discharged it is better than the drinking water you get from the tap. We can only speak for our own fibres, this does not mean that other superwash treatments follow these procedures. We are very particular about where our wool is superwash treated. Jeni has personally been to visit the Superwash treatment plant in the UK that process our Bluefaced Leicester, and this was a really interesting visit, the owner has PhD in this area and employs the most up-to-date superwash techniques and is always trailing new ideas. Jeni is also constantly reviewing the biodegradability studies of superwash yarns, and there is some great research being published on that front. So… what does the process involve? Again please note this is only relevant for our yarns, it may not be applicable to other superwash fibres. Firstly the wool is treated in chlorine to dull the edges of the scales of he wool, this reduces the ability of the scales to stick to each other and therefore reduces felting. Secondly, a resin is applied and creates a microscopic web-like structure permanently bonded to the wool, this smooths the scales, improving the handle and preventing felting whilst maintaining the dyeability. Recent studies have shown that the type of superwash wool we use, biodegrades very quickly in composting and marine environments, the good thing about the resin used on our wools is that it is a fairly weak structure, (unlike other resins which are applied to other types of shrink resistant treatments and may resist breaking down) which means it is a great option because it has shown in studies to break down very quickly leaving no residues. The other shrink-resistant treatments also inhibit the dyeability of the wool which is why they are not suitable for our yarns. On balance we like superwash yarns because they improve the longevity of the yarns and make them more accessible to people where hand washing would not be feasible on a regular basis.“
In addition, the BFL, Blue Faced Leicester yarns I stock are OEKO TEX certified which means they have passed rigorous tests and they are safe for people, the planet and have transparency and traceability throughout the production processes. (including superwash treatment.)
So, combined with natural dyes, these yarns are a meaningful and conscious choice for those wishing to make their yarn crafting more sustainable and environmentally friendly whilst having the convenience of easy washing of the yarn.
Added to post: 25/11/2024
Further to an interesting comment from a blog reader, I have gone back to the manufacturer for further clarification on their superwash process. Here’s what they said:
The most recent study about biodegradability is here https://woolnews.net/2024/07/25/research-confirms-wool-biodegrades-in-marine-environments/
‘Resins are not always plastics (and definitely not in this case) they can be man made or occur naturally – tree resins for example, they are just long chain polymers, but these can be broken into their chemical compounds under the right conditions, and that’s what happens to superwash, it’s not coated on the wool, it’s like teeny tiny dots on the scales and makes up a tiny percentage of the wool, once it starts to break down/ferment these long chains break down into their chemical components, it’s not like plastic which stays as tiny pieces of inert material.
Off the top of my head I can’t remember exactly which resin is used, but I think it is polyamide-epichlorohydrin, it is also use in paper making, toilet paper, tissue paper, normal paper, in all sorts of things that we use all the time, even tea bags sometimes and hundreds of other products we use every day. The way it is used in the superwash process is safe, the processing plant has to adhere to really high levels of environmental standards as its in the EU (This is why we never purchase superwash wool from China because its not regulated there) It is also biodegradable into safe components especially in association with wool, as the wool aids the fermentation break down. I had a long interview a few years ago with a scientist who studies this and so I feel really comfortable with what we use.’
Full disclosure – I dislike superwash yarns and avoid using them wherever possible. The whole idea of taking a beautiful natural fibre, then dunking it in chlorine and coating it in ‘resin’ for the sake of convenience and better dye absorbtion sits very uncomfortably with me.
The above article is interesting but light on detail. What exactly is the ‘resin’ they refer to made of? I’m aware that most treatments use the Hercosett process developed in Australia, and if it’s that, it’s made of a polyamide-epichlorohydrin. Some clarification would be very helpful – they claim that it breaks down quickly leaving no residues and safe in composts and the marine environment. Hmmmmm – there’s increasing evidence that a large proportion of fish have ingested microplastics, which then end up in our food too!
If you really want a “meaningful and conscious choice” to make your yarn crafting “more sustainable and environmentally friendly” use natural, minimally processed wools which haven’t had unnessary and potentially harmful extra processes added. It’s worked for sheep for thousands of years!
I agree Sarah.