A worsted (left) and woolen (right) yarn in the same fiber. The woolen fiber has been fulled.
So you had 500 yards, you washed it, beat it, and now you have 420. Follow that up with a few choice curse words and let’s figure out what happened.
Allow me to introduce the term fulling. Felting is what happens when fabric is agitated enough to cause frictional force to hold the fibers in the fabric together permanently. Fulling is what happens when yarn is agitated enough to cause frictional force to hold the fibers in the yarn together permanently.
When done intentionally, fulling can help yarn to hold together and to bloom of fuzz up. It adds strength to a woolen yarn and can give fibers like mohair and angora a halo St. Peter would be jealous of.
To full yarn, apply our magic formula for felting.
WOOL + MOISTURE + HEAT + AGITATION = FELT
Judith Mackenzie’s method of using a sink plunger may be my favorite. She has a large container of hot water and a large container of icy cold water. She then transfers her yarn back and forth between the two extremes, plunging it a few times in each bath to shock and full it.
When fulling yarn, you can expect to lose anywhere from 20-60% of your yardage. That is a huge range! It depends on a number of factors, including fiber type, preparation, and draw type. This could easily impact a project, so this is an opportunity for sampling before a larger project. Spin a sample of yarn and measure your yardage before you wash or full the yarn. Next full your yarn to your desired finish. Measure again once the yarn is dry. Apply the below formula to find out your percentage of shrinkage.
A = yardage before fulling
B = yardage after fulling
(A – B) / A x 100 = percentage of shrinkage
Once you know the percentage, you can estimate how much yardage you will need to spin to account for shrinkage and it may very well save a future project from going into timeout.