Author of The Complete Idiot's Guide to Knitting & Crocheting Barbara Breiter joins us for her monthly column on techniques that people frequently ask about.
Have you ever thrown a wool sweater into the wash by accident and ended up with a matted, miniature version? That’s called felting. Ordinarily you don’t want to shrink your handmade creations, but sometimes we do it on purpose to create a dense, strong fabric.
|Unfelted Knit Branching Out Bag||Felted Branching Out Bag|
Why Does Wool (and Other Animal Fibers) Felt?
Animal hair fibers felt because there are microscopic scales on them. The scales open up when exposed to hot water and detergent; friction or agitation tangles up these scales, resulting in felt. The result is thick and sturdy, making it ideal for purses and other projects.
Only yarn that is spun from animals or is protein-based will felt such as wool, alpaca, and mohair. Superwash wool won’t felt because, after all, the point is that it's treated to safely throw it in the washer; the treatment either mattes down the scales or removes them so that they cannot lock together. Man-made fibers like acrylic won’t felt and neither will yarn that is spun from plants such as cotton or hemp.
How Do You Felt?
Today, you can felt in the washer; historically people would first place it in boiling water (hence the term "boiled wool") and then create friction with an old fashioned wash board or even rocks.