Kongo gumi, also known as the round braid, spiral braid, hard braid, or strong braid can be formed in two different directions. Each way gives you a similar looking braid, but the two braids are mirror images of each other. The two formations are called S twist or Z twist, depending on the angle of the "stitches" in the resulting braid.
Here are side by side samples of the Z twist and the S twist. Trace your finger over the white stitches, and you will see that they match up with the center "bar" of the letter they are named for. Presently, Z twist braid are the most commonly used in jewelry braiding, but occasionally you will run across an S twist braid. It's a good idea to learn how to make both braids as they can allow you to expand your braiding skills and develop your own style.
Making an 8 element Z twist braid
Begin your braid with eight cords, or four double length cords, in the layout above. The disk photos in this tutorial don't have numbers because each brand of disk has its own numbering system, and I think it's important to learn to follow the cords rather than the numbers. I've marked the disk in four sections that may match dots, directional points, or other special marks on your disk.
Pick up the bottom left cord and bring it up to the top left
Pick up the top right cord and bring it down to the right.
Rotate the disk counterclockwise/to the left.
Repeat all steps until the braid is the length you desire.
Making an 8 element S Twist Braid
Begin the S twist with the same disk layout as for the Z twist.
Pick up the bottom right cord and bring it up to the top right.
Bring the top left cord down to the left.
Rotate the disk clockwise/to the right.
Repeat all steps until the braid is the desired length.
The direction you turn makes a difference!
You may have seen videos or read books, magazine articles, and other kumihimo instructors who state that the direction the disk is turned doesn't matter. This is one of those pieces of information that is true in a certain circumstance, but not in all of them. For an 8 element braid, without a specific bead loading pattern on each cord, turning clockwise/right or counterclockwise/left won't make a difference. The reason it doesn't matter is because there are only two sets of elements to work with, and whichever direction you turn you will be working with the next set of elements you should be. For braids with more elements, be it 12, 16, or more, the direction you rotate changes which set of elements you are working with. This has both a visual and a physical structural effect.
If you look at the photo above, you can see that the left half of the braid is a smooth, even Z twist. On the right half, the braid is still a Z twist, but the "stitches" are uneven, and if you touched the braid, you would feel a ridge where the stitches are overlapping each other instead of lying next to each other.
This photo shows how visual elements are affected by the direction of disk rotation. The kumihimo pattern generators at Craft Design Online or Friendship-bracelets.net both build their pattern layouts on Z twist braids with counterclockwise/left turning. As you can see in the photo above, when you make the braid with a "modified" Z twist—that is, bottom left up, top right down, turn clockwise—the cords are moved out of order, leading to a broken or incorrect pattern in the braid.
Applications for the S and Z twist in expanding your braiding skills
One of the things I was most intrigued by when I started braiding was kongo gumi/round braids that changed directions as they were made. Once you learn the S and Z twist, you can combine them to make some beautiful pieces.
This is a 16 element S and Z twist braid made with four colors that shows the directional changes make the braid into chevrons.
This 16 element braid was done with eight elements of each color to make wide chevrons.
This eight element beaded braid not only alternates S and Z twist, it has beads.
The secret to changing between S and Z twist is this: Flip the cords in each pair. In these illustrations, I am showing only o