What does ‘superwash’ mean?
If you’re a yarn fanatic you’ll undoubtedly have come across the term ‘superwash’. Superwash refers to a treatment applied to wool fibres the makes them resistant to felting and more suited to machine washing (though it doesn’t mean it will withstand any wash cycle). Contrary to popular belief, not all Merino is superwash, but there is a lot of superwash merino on the commercial market so the term has become particular associated with Merino.
What is superwash treatment?
We see a lot of misinformation about superwash treatment on blogs – it is not a plastic coating as often stated. Wool felts because its fibres are coated in tiny scales that open out and become become interlocked when exposed to friction and/or water and rapid changes in temperature. Superwash treatment prevents the scales interlocking using a two-stage process: First, a chlorine treatment dulls the edges of the scales this reduces the ability of the scales to stick together. Then, a micro-fine coating of resin is applied which bonds to the wool, smoothing the scales onto the shaft of the fibre, which prevents the scales opening out and makes the yarn feel smoother. The resin is biodegradable and breaks down with the wool when its useful life is over.
What are the benefits?
- Garments can safely be machine washed. Modern washing machines use less water than hand-washing, therefore reducing the environmental impact during the lifespan of a garment.
- Garments have a longer lifespan because accidental felting is unlikely (we’ve been there).
- It gives wool a softer feel against the skin.
- It dyes easily and is ideally suited to our low-impact dyeing process because it requires less water to dye and can withstand rapid changes in temperature without felting.
What are the disadvantages?
- Garments knitted from treated yarn spun from delicate fibres like extra fine Merino can ‘grow’ when laundered. It is advisable to not only make a swatch, but wash and block it before starting a project. That said, we haven’t had this problem with any of the yarns in our permanent range.
- It cannot be used for intentional felting (it sounds silly, but we have to mention it).
What is the environmental impact?
the superwash yarn we use is treated either in UK (in the case of our British wool) or in South America, which both have extremely strict laws controlling effluent in waste water. As a result the effluent is recycled and water discharged is actually cleaner than tap water! However, it’s important to be aware that other parts of the world are still unregulated, and superwash yarns from other sources may contribute to chemical pollution.
The process does have a chemical, water and energy footprint, but we feel that this is likely to be offset by the low-impact dyeing process it makes possible, the extra wear the garment will receive and most significantly, the reduced water and energy required for laundering throughout its lifespan. These factors are extremely difficult to quantify, and are something that the eco-conscious stitcher will want to consider when deciding if superwash yarn is right for them.