The process of turning loosely knit wool fabric into wool felt is called fulling or, more commonly, felting. It's so cool, it's like magic.
A couple of Christmases back, I made my mother's husband (Hi, Jeff!) a pair of slippers using this process. After a couple of years of hard wear, he's worn a hole in them and he needs another pair. I'm happy to oblige -- I love it when something I've made is so well loved that it gets worn out.
First, I loosely knit a gigantic pair of the slippers:
How gigantic, you ask?
Jeff's feet are not, in fact, 15+ inches long, as the tape measure shows these are. Here is a photo showing the pre-felted slippers I have just knit, compared to his old slippers (in the correct Jeff-foot size):
Next, I throw them in hot water in the washing machine with a pair of jeans to rough them up and a bit of dishwashing soap. In about 30-45 minutes, voila!
See? They've shrunk down to be the same size as his original pair:
Hopefully, he likes these as well as the originals. I like the new color, but am somewhat suspicious of that fuzziness.
Meanwhile, I took the hole-y pair home to see if I could repair them:
Since felt is basically magic, I've got some ideas that might take care of it.
That, however, will be a post-Christmas activity. (Anyone else in a blind only-ten-days-til-Christmas full on panic right now, or is that just me?)
PS -- For anyone looking to make these slippers, I used this very popular pattern from Fiber Trends.