Boiling/Fulling/Felting Wool

This post may contain affiliate links - read the disclaimer.

One of the really amazing features of wool is that you can shrink it into a fabric that is wind, water, and abrasion resistant. “Felt,” as it is commonly referred to, is a great material for bags, outerwear, or, when made with finer weight yarns, many apparel items. The process is known variably as boiling, fulling, or felting wool, and works well with some other animal fibers, too.


This tutorial explains how to turn knit wool into felt without a washing machine, and how to swatch your yarn to be sure your project is the right size when you’re finished.

Boiling Fulling Felting Wool

Boiling Fulling Felting Wool


– wool, alpaca or other natural yarn (at least 60% animal fiber, but ideally 100%)
– knitting needles – 1 size larger than the label gauge is best
– measuring device
– large stew pot or similar container for boiling
– tongs, spoons, other devices to keep your hands away from the boiling water
– gentle soap (optional)


First, knit a swatch with your yarn. This is 40 stitches wide and 30 rows long.


A large swatch is best for accuracy, but if your project is flexible on size you may be able to use a smaller swatch (or none at all, as I did when I used up some scrap yarn to make a bunch of little felt mice for some kitties I know. I’ve found that cats aren’t very concerned with gauge.)

Boiling Fulling Felting Wool

Boiling Fulling Felting Wool

Measure your swatch before shrinking. This isn’t that important, but it does help you track how much your work shrinks.

Boiling Fulling Felting Wool

Place the swatch in a pot large enough for it to move around a bit. Fill the pot with lots of water and crank up the heat.

Boiling Fulling Felting Wool

Bring it to a boil. Use tongs to remove it periodically to check the size. It should be obvious but, this swatch is boiling hot, be careful not to burn yourself.


Don’t leave it unattended. Mine worked like this: no change… no change… no change… no change… poof! an inch smaller.


If your swatch isn’t shrinking as much as you’d like, try a drop of soap in the water. Be careful that it doesn’t boil over, but the soap may help encourage the fibers to tighten up more.


When you’re happy with the amount of shrink carefully remove it from the water, then run cold water over it to stop the process and make it easier to handle. The swatch might be a little wonky (the cast on was slightly smaller in this case.) You can place the felt between your palms and rub your hands together to tighten up small areas. You can also encourage it to dry into a shape you want by arranging it carefully when it’s wet – the way it dries is the shape it will be, unless you saturate it with water and try again.

Boiling Fulling Felting Wool Boiling Fulling Felting Wool

Measure the swatch again after it dries. This is your actual gauge. In this case:

30 rows = 4.25 inches
40 stitches = 10.25 inches


Yep, the swatch is much shorter but slightly wider than the before. When planning your project you’ll want to use this gauge, rather than the pre-shrink version. For example, a 12 by 12 inch square would require 47 stitches and 85 rows. Different stitches will look different when shrunk, and shrink to different sizes.


A few definitions:


boiled wool – Wool that has literally been boiled to shrink it.

fulled wool – Wool yarn that was knit/crocheted/woven/etc. and then shrunk, usually by boiling or washing in a washing machine on hot (intentionally or not.)

felted wool – Nothing in this tutorial is actually felted. Felting is a totally separate process where loose wool fibers are laid across each other and joined through a process of stabbing with a needle or rubbing together. The finished textiles look really similar to boiled/fulled wool so the terms tend to be used interchangeably, but they really are different.


A few notes on materials:

Of the two most available wool yarns in American craft stores, I find that Pattons Classic Wool felts down a lot more dramatically than Fisherman’s Wool. This is neither good nor bad, but may be useful based on your situation. Superwash wool won’t felt at all – that’s it’s job. It’s treated so you can toss it in the washing machine without creating an unintended doll-size sweater tragedy. Alpaca shrinks to the most magically soft fabric I’ve ever worked with. Cotton doesn’t felt/full, but it does sometimes shrink a bit when boiled, which can be an interesting look in some circumstances. Acrylics, polyesters, nylons, and other synthetic fibers are totally useless for fulling, don’t waste your time. Other animal fibers and blends with things like mohair, angora, and silk may or many not shrink, they definitely need to be tested. In almost all cases fulling/boiling makes wools and angoras so much softer, so it might be a good thing to test with that gorgeous yarn in your stash that’s too scratchy to use!


Update: I tried this same method with some Paton’s Classic Wool in “Aran” (a creamy off white color) and it did not work. At all. It shrunk a tiny bit but didn’t fluff up or look felty. Light colored wools are generally more likely to be difficult to felt, but it was still disappointing. So, to re-re-repeat myself, swatch first!