When it’s coated with plastic. Like the kind I have to hide from Arya because things like this happen…
Two years ago, in my post about plastic-free kitting, I mentioned I was knitting slippers out of Superwash wool from Lorna’s Laces. I assumed that Superwash meant the yarn had already been washed and wouldn’t shrink anymore. I guess I was thinking of cotton. Anyway, an astute Fake Plastic Fish reader Rebecca left a comment on that post just a few weeks ago letting me know that Superwash wool is actually coated with a polymer to prevent the wool from shrinking. (It’s nice to know my posts hold up over time.)
Turns out, there are two methods used to create this stuff. According to About.com’s article on Superwash wool,
It can be made using an acid bath that removes the “scales” from the fiber, or it can be made by coating the fiber with a polymer [read: plastic] that basically keeps the scales from being able to join together and cause shrinkage.
So I emailed Lorna’s Laces to find out how their Superwash wool is made. Here’s the response I got back from Beth Casey:
Lorna’s Laces is not a mill so we don’t do the superwash processing, but I can tell you what I know.
The acid used is generally chlorine based and the polymer is polyamide or nylon. Our yarns use a two step process that incorporates both.
Oh my. Not only do they use plastic on the yarn, but also chlorine-based acid which is terrible environmentally. Guess I won’t be choosing that wool anymore. And maybe in the future, I’ll knit my slippers out of regular organic wool and felt them.
Do you have suggestions? What is the most eco-friendly yarn that also is able to be washed without shrinking? Things like slipper socks can get awfully dirty. (Or will I have to just soak them in cold water?)