“what?” I hear you cry. Well the direction your yarn is spun in makes a real difference to it’s splittyness (is too a real word) along with your preferred craft. If you hold your yarn vertically in front of you you will see the twist slopes either to the left or the right.
If it slopes to the left then it is a Z twist
The twist runs in the same direction as the slope of a Z, this is the better twist for crocheting, we’ll get to why in a bit.
If it slopes to the right it is a S twist
The twist runs in the same direction as the slope of a S, this is better for knitting (and most common).
Now because of the action of hooking the yarn right handed an S twist will untwist
See how the second loop (the one on the left) is starting to unravel? that is because of the S twist, as you hook the yarn it is twisted in the opposite direction to the twist, this does not happen with knitting so as knitting is the more.. well known craft most yarns are S twist. It does need mentioning that not all S twist yarn is splitty fibre content plays a part too, but that’s a story for another day.
I heard that left handed hookers don’t experience the split
If you look at the last picture the second loop (the one on the right) the twist has stayed… twisty. In using my left hand I have twisted the yarn WITH it’s own twist. Now I understand that not everyone can swap hands like that, and to be honest right handed is more convenient for me, so if you have a non grabby S twist yarn there is a little trick you can do, if you roll the yarn with the S twist a little to over twist just before you make your stitch it it is just right by the time you have finished the stitch, this can take a little practice but eventually it becomes automatic.
A quick note on Z twist and knitting
King Cole Riot is my favourite yarn, I made bears with it
I love it, although the weights are off in my opinion so the DK is more of a 4 ply. I have started knitting a pair of socks with it and it is a Z twist, so all the problems associated with S twist and crochet are showing up on my lovely socks and I haven’t practised the twist with knitting.