Tuesday, May 10, 2005

Question from Reader: Yarn Differences, Part II

What I understand from my research is that acrylic is made primarily from acrylonitrile.  Acrylonitrile is a rubber substance that when heated, softens; and when cooled, hardens.  As it's heated, it allows for fibrication -- for creating some of the common products we know as polyester, nylon, spandex, and acrylic.  In simple terms, the more it's heated in production, it makes for a softer product ... like acrylic yarn.  Because acrylonitrile is not a natural substance like wool or cotton, it's called a "continuous filament" and may be directly formed into yarn without the additional processes that natural fibers need (i.e., carding, combing & spinning). 

From there the yarn is either twisted into the Z-twist (counterclockwise) or the S-twist (clockwise).  This is to give the fiber strength.  The more it's twisted, the stronger it is.  There are cases where both twists are used to create an end product, but since I have no personal experience of spinning yarns -- yet!, I'll stop my thought process there.  I do know that once the yarn is twisted with other strands it creates what we know as "ply."  Each ply that's added can be of the same twist, or different (it creates variations in the end result).  Interestingly enough, I found out this tidbit at the Fabric University: "Generally, woolen and worsted yarns are S-twist, while cotton and flax yarns are typically Z-twist." 

Now, as to yesterday's challenge ... did you try it?  When we crochet we notice a phenomenon happening -- our yarn twists as we create each new stitch!  This means
that as we are crocheting we are either twisting the fiber more (makes for a slightly stiffer fabric) or we're untwisting (making for a slightly softer fabric).  It all depends upon: 
            1. If you're a left handed or right handed crocheter
            2. If you pull your fiber from the inside or the outside of the skein.
3. If the yarn is primarily a Z or a S twist.

So there you have it.  A yarn's softness has to do with how it's processed/created (including the dying process: natural dyes verses synthetics); how it's twisted (slightly to tightly); it's number of plies (don't forget the ply's themselves have a twist variable too!); and if it's being twisted more, or less depending upon the crocheter. 

If you get a chance to experiment, buy yourself a little bit of unspun roving ... pull from the roving a continuous strand and crochet it up.  You'll really notice the twisting that happens with your crocheting!  Also, before you start a new skein of yarn, inspect it.  Check out it's twist!  :)

Trivia:  Do you know what natural fiber is the only "continuous filament?"  I'll give a clue:  It's eggs were first smuggled into America hidden in women's hair!  ... oh! what we do for the love of our fiber!


Anonymous said...

silk - it has to be silk!

Anonymous said...

I agree with the silk.  The eggs are the tip off!

Thank you VERY much for posting this.  It makes more sense now.  I do notice when I'm working with thread, in particular, that it starts to twist more as I work with it.  Sometimes, I have to stop and let my work "unwind" before I can continue.  Is this the same thing that you are referring to?