When we first learned to spin, we all started by spinning a singles yarn. Then came the next step: Plying. We were most likely told by our instructors or mentors that we had to spin the opposite direction to ply but being occupied by attempting to spin our first singles, we may well not have heard this bit of information or didn’t register how important it was.

Let’s start at the beginning, with spinning singles. When we learned to spin singles, we were taught to have the drive wheel turning towards the right or in a clockwise direction. When the drive wheel is turning clockwise, the direction of the twist inserted into the yarns is referred to as “Z” twist because the twist angle in the yarn matches the middle stroke of the letter Z. Since this is the normal direction for spinning singles, we filled our bobbins with Z twist singles yarn.

Then we got to plying and may have recalled our instructor saying ply in the opposite direction.
But how and why? And won’t going in the opposite direction remove the twist?

The how is simple: Place the bobbins of singles onto the kate, place an empty bobbin on the wheel, thread the leader through the orifice and attach the two singles to the leader. Start the wheel so that the drive wheel is turning towards the left or counter clockwise. When the drive wheel is turning towards the left, it is inserting “S” twist, so called because the twist angle of the yarn matches the middle stroke of the letter S.

When plying, the “drafting zone” is between your hands. Your backhand should keep the two strands of singles separated and lightly tensioned until they move into this zone. Your forward hand controls the amount of twist entering the plying zone.

The why is easy to understand when thought about in terms of twist direction. Z twist goes towards the right; S twist towards the left. If you plied two Z twisted singles with more Z twist, you would be adding more right twist. By plying two Z twist yarns with S or left twist, you are removing some of the Z twist and adding S twist. The added S twist basically neutralizes the effect of the remaining Z twist, balancing out the tendency of the singles to slant towards the right. When the S and Z twist are balanced, the yarn is balanced, and the skeins will hang straight when finished. The individual fibers composing the plies of the yarn will also appear to be straight.

Plied yarns are more stable and stronger than singles yarns, wear better, and pill less. Inconsistencies in the spinning of the singles tend to even out in plying and in finishing the plied yarn.