Shrinking Wool

In an effort to shrink my wool slippers to make them fit better and with much help from others on this site, I took the plunge and decided to throw caution to the wind and tossed the slippers in a hot wash/warm rinse and let the washing machine run its course. When they came out they looked smaller and a bit more densely packed, which is a good thing in slippers. Since they are knit with two strands of yarn, I didn't want them to stay damp too long, so I put them in a low dryer for about 15 minutes. They shrunk a bit more and fit even better now. Since they are 90% wool and 10% other fibers, I imagine they didn't shrink as much as 100% wool might.

I am now making a pair for my son and am making the smaller size, so perhaps they won't need shrinking to fit him. I have also decided to use 100% pure wool in a nice bright blue...his favorite color. I have also changed the yarn to one strand instead of two and chose the #5 bulky (100g/3.5oz, 109m/120yds) instead of the #4. It's a lot nicer to work with and looks great. I just finished the sole this evening. The wool yarn is by Patons and is called Classic Wool - Roving, which is smoother than the Tweeds version from the same company. I'll post a picture once they are finished.

In the interest of increasing my knowledge of the science of yarn, I did a bit of research and present three pictures for all who may not know what wool does when it is 1) tumbled about in a washer and dryer, and 2) washed in hot water and rinsed in warm. I also offer two articles I stumbled upon that explain why wool shrinks as it does, as well as an article from 1938 about the "newly discovered" chemical treatments that prevent wool from shrinking.

Why Does Wool Shrink?
Shrink-Proof Wool

Below are pictures of the yarn and the slippers. The last picture is a side-by-side comparison of a slipper before and after shrinking - top= preshrunk, bottom=shrunk (felted).

Thanks to the guys who gave me some good information before I risked the shrinking process.

Okay, class dismissed.


Image icon before_after 1.JPG136.85 KB
Image icon before_after 2.JPG121.36 KB
Image icon before_after 3.JPG184.48 KB


Joe-in Wyoming's picture

Very good...I'm glad it worked out just as planned. With the 100% wool, of course, you'll need to check it more carefully. [Or, at least, that is what my felting friends tell me.] I'm unsure about using a dryer as part of the process, though. That needs to be answered by someone with more experience. -- Books, knitting, cats, fountain pens...Life is Good.

Books, knitting, cats, fountain pens...Life is Good.

CLABBERS's picture

I agree, Joe. I figured I had already had so many issues learning the process to knit the slippers that I might as well go all the way and see what other trouble I could get into. As it turns out, all is well and the slippers feel great. Of course, now that winter is over, I don't really need them. I'll get good use out of them next year.

Joe-in Wyoming's picture

My felted slippers [commercial, not homemade] were used all year round. That is probably why they wore out so quickly. Enjoy them. -- Books, knitting, cats, fountain pens...Life is Good.

Books, knitting, cats, fountain pens...Life is Good.

Bill's picture

Yes..the dryer is good. The more you can agitate the wool while felting the teacher had me stomping on it, and slapping it against the table...all during the warm water and soap process...alternating with cold water baths to shock it. All of this opens up the scale of the wool so it will lock with the scales next to it. ...but a bit of dampness for blocking is good to. If it's a hat, you can stretch the shape a bit before it's completely dry to finesse the shape.

CLABBERS's picture

Thanks for the advice, Bill. I felt like stomping on the first slipper while knitting, and I believe I did slap it a few times on the table. That was, however, more out of frustration than anything. Wool seems like such a durable material. It's kind of like us, the more life has its way with us, the stronger we get, at least so far...sciatica notwithstanding.


Tallguy's picture

Felting and fulling are quite different, and I won't go into all the detail about the difference between them. The major difference is in the preparation of the fibres.

We have made felted booties or slippers by taking carded batts of fibre and wrapping it around a foot into the basic shape of a boot or slipper. Then we would stomp around in a tub of soapy water! This is the best fun! Remember how you made new jeans fit YOU by soaking in a tub of water while wearing them and then letting them dry on you.

It is the agitation that causes the fibres to rub against each other, and the scales to catch on each other and create the interlocking of the fibres. The presence of soap and water allows for more freedom of movement and therefore interlocking. But you will notice that your wool socks will also matt on the sole and possibly the back of the heel where there is some rubbing, without the presence of water and soap. We also do felting on dry fibres with the use of a barbed needle which interlocks the individual fibres.

It should be noted that matting occurs much easier in woolen spun yarns than worsted spun. When using batts, you will want carded batts as opposed to combed top. While any of these will felt, some work faster than others. Some breeds of sheep do not matt at all (they do not have as many of the scales or crimp).

By shaping these boots on the individual foot, it then will fit perfectly. You are also in control of the amount of felting you wish to cause. We have also followed the same principle in making hats. The actual shaping of the hat happens on your own head making it a perfect fit. Felting is a wet messy process, but what fun! It's only water, after all. People do not shrink by getting wet!

When the item is created from yarn and then formed into a textile of some sort, and then allowed to have some felting occur in the textile, that is called fulling. We often do this after weaving a fabric and we say the yarns are allowed to "bloom", which means they open up to fill any empty spaces around the yarns. (see "waulking") Sometimes we will also raise a nap on the fabric by brushing it and causing any loose ends to work free and protude from the yarns, creating more trapped air and giving the fabric a softer feel. Blankets are a perfect example, or "fleece" fabrics.

There is a lot of matting that occurs in the dryer because of the agitation or the tumbling. Most of the wear in our clothing happens in the dryer. So if you have reached the correct amount of shrinkage by washing your fabric, don't put it into the dryer because you will get a lot more! By placing the garment on some form (for 3-dimensional garments) or pinning to conform to a size (as lace blocking or a sweater or socks) or simply by laying flat to dry, you are ensuring that the dried item will be the shape you want. You can sometimes slightly stretch a felted fabric (as in re-blocking a hat) but not much -- it can, however, be made to matt further and made smaller.

CLABBERS's picture

Thanks for all the great information. There is so much to learn about fabrics of all kind.