Mary Corbet of Needle ‘n’ Thread explains the difference between S-twist and Z-twist embroidery thread. She says,
In most commonly used embroidery stitches, you’re not going to see that much of a difference between the way the stitch looks, whether you’re using an s-twisted thread or a z-twisted thread. But there are some exceptions…Stitches that are affected by the twist of the thread include stitches that twist together, such as stem stitch or outline stitch, as well as stitches that involve wrapping the thread, such as the bullion knot.
Find out more from Mary’s blog post. And check her blog tomorrow (January 6) for a demo of the differences.