When new to spinning yarn, you may find yourself asking what is Z twist, and what is S twist, and what difference does it make? This post will clear that up for you!
Z Twist vs S Twist
Z twist or S twist simply refers to the direction in which your wheel or spindle is spinning while you spin your fiber into yarn. If the wheel is spinning to the right as you look at it (clockwise) that is a Z twist, and if the wheel is spinning to the left (counter-clockwise) that is an S twist. (If using a drop spindle, it is the direction the spindle is going as you’re looking down at it.)
What difference does it make, you ask? How you ply!
When spinning yarn, you will always spin in one direction and then ply the yarn in the opposite direction. This helps to balance the yarn, create a stronger yarn, and to remove any extra twist from each of the singles.
Traditionally speaking, when spinning a single yarn (one bobbin) you will use a Z twist. Then when you go to ply that bobbin (either by plying additional singles or a Navajo (aka Chain) ply), you will use an S twist.
Technically speaking, however, as long as you ply in the opposite direction from which you spun your singles, it doesn’t really matter which direction you start with. For example, if you are a crocheter, you may find that the opposite makes a better working yarn for you. (S twist to spin and Z twist to ply.) This is because of how the yarn is wrapped around the hook while you’re crocheting with it. As a crocheter, this matters to me.
As long as you start one way and finish the other, the yarn will theoretically be sufficient for all kinds of uses.
How to tell which twist is which:
To discern whether a yarn was spun with S or Z twist, look at it vertically. Yes, even commercially made yarns.
The fibers will either run top left to bottom right like this in an S twist:
Top right to bottom left, like this in a Z twist:
If you think about the center part of the letters S or Z, you can see why the first is called an S twist while the second is called a Z twist. Cool, right?
If you’re looking at a yarn that has already been plied and the fibers run top left to bottom right, that means that it was plied using S twist, and – if done correctly, originally spun using a Z twist.