Why Wash?

So, I'm home and settled in and getting caught up on my emails.  I found this wonderful question on one of the lists I follow, and I just couldn't resist the opportunity:

Hi everyone - I have been thinking about washing yarn and setting twist, etc.. When you spin a yarn you always wash it to set the twist and also to get out any yuckies that are left. Then when you knit with this yarn, you wash or wet the piece again before you block. Could one save a step and just spin, knit and then wash? Has anybody done any experiments with this to see if there is a difference doing it one way or the other?

Well, it just so happens that I have done experiments, and here is what I have discovered:

YOU MUST  ALWAYS WASH AND SET YOUR TWIST BEFORE KNITTING OR WEAVING WITH YOUR HANDSPUN YARNS.

Okay, so I'm shouting.  But with good reason.  You see, when we spin, no matter what fibre we use, we are stretching the fibre out to it's full length (drafting), and then holding it under tension as we force twist into those stretched fibres.  The stretched and twisted fibres are then pulled onto a bobbin, maintaining the tension.  As long as we keep those fibres under tension, they will hold the twist exactly where we put it during the spinning.  The fibres wills stay elongated, the twist will lay dormant under the stress of the tension.  All is good, right?

Well, as long as that yarn stays on that bobbin, yes.  Sitting there on the bobbin, that yarn looks all smooth and balanced and pretty.  But looks can be deceiving.  That yarn is under tension.  It is not ready to relax and cooperate just yet.  When you wind the yarn off onto your niddy-noddy to make a skein, you see what happens to that yarn.

A well-spun, balanced yarn should come off of the bobbin with some residual twist.  If your yarn comes off and makes a perfect U, your yarn is actually underplied.  You want to see this yarn twist up like this.

Why?  Because, in order to have enough ply to hold together in the working and create a balanced, smooth fabric,  you have to ply your yarns with 2/3 the amount of the twist that you put into your singles.  If you ply at 1/2 the singles twist, you will find that your yarn is unstable and that your fabric will seem uneven and may even skew.  Trust me, I've tried it.

"Okay, Ms Smarty-Pants," you say.  "I don't wind my yarns off onto a niddy-noddy, I use a ball winder."

That's fine, but what you're doing when you do that is maintaining the tension that the yarn has been held under on the bobbin.  Until you start pulling that yarn out and knitting or warping with it.  Then all that tension lets go and the twist runs rampant.  Little pigtails start snarling the yarn, and, invariably the yarn snarls inside the ball, creating a tangle.  Who needs that?

When you put yarn in hot water, something wonderful happens.  The individual fibres relax and try to return to their natural state, releasing the tension that we have tugged into them.  They fall into a softer arrangement, and create more space in the sideways direction.  The twist then finds more space to spread itself out and no longer tries to pull those fibres in it's own direction.  Balance is achieved.

Now your yarns have that perfect U. 

I did this little demonstration with two different fibres, treating them both exactly the same after they came off the bobbin.  The orange skein is Corriedale top (wool) and the purple skein is silk.  As you can see, the setting of the twist is vital for balancing the yarns in both fibres, but far more so for the silk.

When you go to work with the yarns, washed or unwashed, you will see a dramatic difference in the way that yarn feels and acts.

Let's look at the knitted samples before blocking.  The sample on the left is the unwashed yarn.  You can't see it in the photo, but it had a harsher hand and tended to snarl as I knit with it.  You can see, however, that the work curled and skewed as I knit it.

This effect was far more dramatic in the silk sample, which, let me tell you, was not fun to knit in the unwashed version!

Another interesting thing happens when you set your twist in hot water.  The wool sample came off the bobbin measuring 3 tpi and 14 wpi.  After setting, the same sample measured 4 tpi and 12 wpi.  The silk samples came off the bobbin at 6 tpi and 32 wpi, and was 9 tpi and 30 wpi after setting.  Ummm, the unwashed yarns are very different from the washed yarns.  Very.  And this will impact what they do in the fabric.

For one thing, the gauge of you knitting will be different.  The wool knitted up at 8 stitches/inch when it was unwashed, but 6 stitches/inch when washed.  The silk, 12 stitches/inch unwashed, 10 stitches/inch washed.

If you knit, you know what a huge difference 2 stitches per inch makes in the size of your garment.  If you don't knit, take my word for it--it's not good.

After blocking, you can really see the impact of washing and setting.  The top sample is the unwashed, the bottom is washed and set yarn.  I rest my case.

You will also notice that the unwashed samples are more open and less dense.  If I had a better camera, you would also be able to see that the stitches are not as tidy in the unwashed samples, showing uneven twist throughout and creating that notorious "bar" that happens when yarns with unbalanced twist are knitted.  And then there is the skewing...

So, does that answer the question? 

Good.