Felting (also known as fulling) wool fabric is simple. In fact, many people have discovered the principles of felting wool by accident when they washed a favorite wool sweater into doll clothing! Felting is a process of shinking the wool fibers and allowing the little scales on the fibers to interlock, making a tighter fabric that is more water resistant. Wool that is tightly felted will not ravel when cut, so it can be used for making purses or other items where you might want to use a decorative non-raveling edge.
Wool felts with:
- Temperature changes
- Alkalinity (pH of the water)
So, to felt wool all you need to do is provide heat, agitation in the washing machine, and if desired some pH changing detergent (also known as laundry detergent!). I usually don’t bother with detergent, but occasionally I’ll add a small amount of detergent if I want to be sure that there is no extra dye in the fabric that will come out later or if I just want to make sure the project is REALLY felted.
Felting wool is kind of like ripening a banana. Green, green, green, brown! If you are not careful you can miss the moment when the wool goes from perfectly felted to oops! If you are felting wool fabric for use in a coat or wool diaper cover or something where the idea is just thick and water resistant then it does not matter how felted it gets so you can be less careful. If you are felting a wool sweater to cut up for a diaper cover or if you are felting something where the dimensions matter, then you need to stop the washer and check it from time to time so it does not shrink too much. I also learned to watch out for thick fabrics. Some of them get too thick and stiff if I overfelt them.
Wool blends will stop felting at some point, 100 percent wool will shrink much more. I prefer 100 percent wool although you can felt wool with up to 20 percent synthetic fiber in it. Wool that has been treated so it is washable will not shrink or felt much.
I felt wool fabric (or wool sweaters) by putting them in the washing machine and running hot water. I use just enough water to cover the item, so usually I set it on small load. You get more agitation with less water. Then, I set it to agitate on high. If it is something where size matters, I check it every 5 minutes or so. Stop agitating when it gets close to the right size or thickness as you will get some more shrinking when it rinses, a little more when it spins out and even more if you put it in the dryer. Rinsing is only necessary if you used detergent, so you can skip right to the spin cycle. My washing machine adds a little cold water during the spin cycle to get rid of any suds. It took me a while to figure out WHY it was felting my wool so much more on spin. Changing from hot to cold water will cause the wool fibers to shrink up some more.
If I want to really, really felt some fabric (such as thickening wool crepe up for a bed pad) I let it go through a whole washer cycle and then throw it in the dryer to shrink a bit more.
I get my wool fabric cheap at Fabric.com. They have nice wool flannel, crepe, and other 100 percent wool fabrics for as little as $4.98 per yard.