On a yarn label, the letters “SW” or the word superwash mean wool that has been treated to be machine washable. Here is what the treatment changes, what it doesn’t, and how to choose between superwash wool and untreated wool.
Superwash is very common in sock yarns, baby yarns and any project that will be worn and washed a lot. But “machine washable” doesn’t mean “no care needed”: it’s worth knowing what it involves before you choose.
What does “superwash” mean?
Wool fibre is covered in tiny scales. When wet, agitated and warm, these scales hook onto each other: that is felting, which makes a sweater shrink when washed too hot.
The superwash (SW) treatment is a clever finishing step designed for everyday life: the fibre is made smooth, so the yarn can go through the machine at 30 °C, or on the programme shown on the label, without felting. It keeps the look and warmth of wool, with a softer feel and a light sheen.
How is superwash wool born?
Before it reaches your basket, the wool receives a gentle treatment: its scales are softened, then the fibre is wrapped in a fine protective layer that makes it smooth and soft. There are several ways to do it, some newer and gentler than others.
The result? A yarn that keeps all the magic of wool, ready to be dyed in deep colours, then knitted, worn and washed without a worry.
The benefits of superwash
- Easy care : machine wash on a wool or delicate cycle, with no fear of shrinking.
- Good wear resistance : ideal for socks, children’s cardigans or everyday garments.
- A soft feel : the treatment smooths the fibre, which suits sensitive skin.
- Bright colours : superwash wool takes dye very well, which is why hand-dyers love it.
Its limits
- A less “woolly” yarn : less loft and bounce than untreated wool.
- A softer drape : a superwash piece can stretch in width and length with wear or after washing. Be sure to block it well and knit with a good tension.
- An industrial treatment : the yarn goes through an extra production step, which some people prefer to avoid. It’s a personal choice: pick the wool that suits you. : it requires chemicals and a lot of water. Wool industry sources say modern plants recycle their water and respect discharge limits, while others remain critical of its impact. Make up your own mind and choose knowingly.
Superwash or untreated: how to choose?
Choose superwash if the piece will be washed and worn often: socks, children’s clothes, gifts for people who don’t want to worry about care. Choose untreated wool for a shawl, sweater or hat that you will wash by hand, rarely: it offers more bounce and character. Washed gently by hand or on a wool cycle, it won’t felt.
Three examples of superwash yarn in our shop
In the LO(U)VE range, several bases are available in superwash, perfect for projects that get washed often:
- LO(U)VE SINGLE : a single-ply yarn, soft and supple, for light garments and accessories.
- LO(U)VE TWIST SOCK : a plied yarn, sturdier, designed for heavily worn socks.
- LO(U)VE FINE SOCK : a fine yarn for light socks and delicate shawls.
Colourways vary with the current dye lots: you will find them on each product page.
Caring for a superwash piece
Always follow the label. In general: machine wash at 30 °C on a wool or delicate cycle, gentle spin, wool-friendly detergent, no fabric softener. Dry flat: tumble drying is not recommended.