How Much Does Thwacking Change Handspun Yarn?

I have always heard that wet finishing and thwacking your hand spun yarn can make a huge difference in how your final yarn feels and behaves in a project. Let’s find the answer to the question, how much does thwacking change handspun yarn with an experiment.

You can watch a video of this thwacking experiment on my YouTube channel.

How Much Does Thwacking Change the Yarn? The Experiment…

I recently spun up two skeins of 2-ply yarn. Both skeins have the exact same fiber-content. I’m going to wet finish one so that we can compare it with one that isn’t wet finished. 

The Fiber

The image shows two braids of fiber. Rust colored merino wool above, and a braid of white, teal, and orange wool and mohair blended together.
Rust colored merino on the top, and a polwarth, mohair, and silk blend on the bottom.

Here’s the luxurious fiber blend I used:

The orange stripe in this yarn is a merino 100% wool comb top that I got from Camaj Fiber Arts.

The white yarn with stripes of blue is a blend of polwarth, yearling mohair, and tussah silk from Blue Moon Fiber Arts.

How to Wet Finish a Skein of Yarn

  • Using a bowl of warm water, open up one of the skeins and set it down into the water.  Press it down to make sure that it is completely covered with water for thorough saturation.
  • Let the yarn sit in the water for about 40 minutes. 

Be careful not to agitate the yarn in the water.  You don’t want the wool to felt!

A metal bowl full of water and a skein of yarn.

Wool and mohair fibers are not just a flat surface—there’s actually a cuticle covering the shaft of the wool.  If you see bubbles coming to the surface, the wool cuticle is opening up and the water is getting in where it needs to be.

  • After a 40 soak, you can be sure that the skein is thoroughly saturated.  Carefully remove it from the water.

When working with wet yarn never  wring the yarn.  The fact that the wool is fully saturated with water makes it fragile, so wringing the yarn with a harsh twisting motion may damage those fibers.

  • Remove most of the water by giving it a gentle, soft squeeze.
  • Set it on a bath towel and then roll up the towel, pressing with every turn, so that more water will be pressed from the fiber.
Rolling a skein of yarn up in a towel to press out the water.
Pressing the water out gently with a towel
  • If you have a salad spinner available, place the yarn in the spinner and give it a good spin to get all the last bits of moisture out.  This will speed up the drying process. 


  • With the skein loops lined up evenly, I grab the skein of yarn, swing it around and whack, or thwack it hard on the seat of a chair.  To make sure that I thwack all the way around the whole skein, I’m going to scoot it a couple of inches in my hand, hold the next section, and give it another swing around and thwack.  I continue shifting a couple of inches and then thwack as many times as required until I’m all the way around the skein and back to where I started.

Any of these surfaces may be used for thwacking: edge of the door frame, edge of a desk or table, bath tub, sink, counter, chair, what have you……

  • After the thwacking process, I hang the skein up to dry overnight.

Comparing the Finished Yarns

Now that the wet finished yarn is completely dry, let’s compare it to the yarn that was not wet finished to answer our question, how much does thwacking change handspun yarn.

A skein of yarn showing one orange ply and one lighter color ply.
The thwacked yarn feels different!

Feel:  The thwacked yarn feels more fluffy and lofty. 

Drape: The thwacked yarn has lost a little bit of drape—even with the silk and mohair in it!

Yardage: As you might guess from the increased loftiness and diminished drape, the yarn actually shrank from the wet finishing.  Yardage is changed! 

Gauge: Because the yarn fluffed up so much, the wraps per Inch also changed.  The yarn that was wet finished ended up with about nine wraps per inch, which is a perfect worsted weight yarn.  The other skein that was not wet finished has thirteen wraps per inch.  Four wraps per inch were lost because of the wet finishing process.   

A graphic listing the changes in the Thwacked yarn and showing the difference in length of the two skeins. The text reads The Thwacked Yarn is
Less Dense
Fewer Wraps/Inch
Less Yardage
Less Drape
Feels Softer
Slight Halo
Feels Fluffy
Thwacked yarn is on the left, Not thwacked is on the right

If you are using the yarn in a project where gauge and yardage matter, ALWAYS re-skein your yarn after wet finishing. You will need to recalculate your yardage because of the “bloom” to avoid overestimating your yardage!

My Conclusion About Thwacking

It is clear to me that thwacking does change handspun yarn quite a lot! In fact, I would say this yarn is not really finished, until it has been thwacked! The two skeins of yarn feel so different! I love how thwacking gave the yarn more bounce and fluff. In the future, it will also be important to take this change into account when spinning to a standard for a specific project!

A full bobbin of yarn surrounded by the finished 2-ply yarn.
This is such a lovely yarn!

If you would like to know how I finish my yarn after spinning on a drop spindle, you can read all about it in this blog post!

8 thoughts on “How Much Does Thwacking Change Handspun Yarn?

  1. Sharon

    Love the instruction! I’ve always placed the yarn in first hot, then cold water a couple times, then used my arms with the fiber around it to jolt it. Is this wrong, or just a different method?

    1. JillianEve

      Great question Sharon! I wouldn’t ever say a method is “wrong” unless you are not getting the result you are trying to get! Yep, there are lots of different methods! The cold water dunking is called “shocking” the yarn. The hot water causes the scales covering the individual wool fibers to open up and the cold water snaps them shut. Within the yarn, the fibers will snap shut onto their neighbors and this causes a little bit of a felting process. It is great for yarns that need a little extra strength against abrasion like a singles yarn. It will take out some of the loft though and cause the wool to become a little more compact, so it might not be the method you want for a fluffy fuzzy sweater. Snapping the yarn, as I call it (I’m not sure that’s a universal term though) is very similar to thwacking. It has the same effect of settling the twist and setting the yarn. I especially use the snapping method when the yarn has a lot of texture and the smacking part of thwacking could diminish some of that texture. I hope this helps! Happy spinning!

  2. Loraine

    Thanks Evie, this was really great information! I have wondered myself why we need to thwack the yarn and I do it because it’s fun 😉 but I will definitely be remeasuring after it’s dried. I’ll be curious to see how much of a difference in yardage there is as well!

    1. JillianEve

      Haha! I do it because it’s fun too!? I think measuring and noticing the difference in your yarns is a great idea! You will find that some yarns spring up more than others but measuring will give you experience to more accurately predict your final yarn and spin the project you really want! Happy spinning!

  3. Samantha

    Hi complete newbie here (only been spinning for a couple of weeks). The question I would like to know is how do you set yarn that has recycled sari in it (once wet it bleeds colour into any white). I use my yarn for weaving. Hoping you know what to do ?

    1. JillianEve

      Hi and welcome to spinning! This is a really good question. I think that the solution depends on why the silk is bleeding. If it has too much dye on the fabric for the silk to take up then it just has to bleed off until the excess is all rinsed out. If it is a matter of it not being fully set then a soak in some water with a generous splash of vinegar and setting it in a steaming basket should work. I think this is worth some experimentation!

  4. Pat A

    Muskox may also be finished in this way

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