It’s ubiquitous, superwash wool. Superwash refers to wool that can be machine washed (and possibly dried) without fear of it shrinking and felting to Lilliputian sizes, thanks to one of a couple chemical processes. The first is a chlorinated bath that removes the “scales” from wool fibres, smoothing them out and taking away their ability to lift up and then stick to each other, which is essentially the process of shrinking/felting. All hair has scales, by the way, even human hair–it’s overlapping layers of the cuticle, which is the outermost part of the hair shaft. Wool, especially certainly breeds like Merino, has lots of scales and is especially prone to felting.
Another way to remove the risk of felting is to coat the wool fibres with a polymer, sort of a plastic outer layer that covers the scales. This is all well and good, and superwash has certainly been a boon to the wool industry in general(and has its uses), but it’s not without problems. First, both the chlorination and polymer processes are quite toxic. That last link also gives some info about a less toxic variation of the polymer process, but I’d like to move on to other issues with superwash:
It kind of makes the yarn suck. I know, I know, them’s fightin’ words, but hear me out. Because there are no scales, the fibres become quite slippery, which explains superwash yarn’s tendency to GROWWWWWW when it’s washed. It can be cajoled back to normal size again, but generally not without the use of a clothes dryer, and it adds an extra layer of complication to something that must be blocked (like lace). It also changes the hand feel, especially if there are polymers involved. It’s taking wool and making it, well, more like acrylic. I’m currently knitting a pair of leg warmers from gorgeously dyed gradient wool, but the feel is absolutely terrible in my hands. Superwash strikes again. (Though it should be noted that this varies greatly among mills/producers. Some superwash yarn still feels quite nice.)
While superwash is a handy quality in commercially produced items like my merino base layers for winter sports, I have to ask myself, do I really need machine washability in my handknits? Most of what I knit will be hand washed anyway, especially the lace, and I even hand wash my socks. I don’t need the superwash quality.
So, I end up with my New Year’s Resolution for 2018: I will not be buying any superwash yarn or fiber this year (though I’ll knit with the stuff I already have). Primarily for the environmental benefit, but also because I just don’t like the stuff as much as untreated wool. This may even be a challenge, because superwash is everywhere, and people seem to look for it on the label even if they don’t end up chucking their finished items in the washing machine.
Feel strongly about superwash? Got a nice untreated wool yarn to recommend? Leave me a comment.