Left Twist Vs. Right Twist Sewing Thread

By Ron Becka

Using thread with the correct twist when sewing with heavy nylon or polyester industrial sewing thread is very important to smooth sewing, which is why it is good to know the difference between the applications of Z-twist(left) and S-twist(right) thread. 

The most common sewing thread is left twist, and this is standard for most single needle sewing machines. The thread twists to the left and the sewing process will increase this twist. Using right twist thread on a single needle machine will cause the thread to untwist or fray, slowing down the sewing process. Right twist thread is generally used for the right hand/outside needle of a double needle sewing machine. 

Please be sure the correct thread is suitable for the purpose intended. Although left and right twist thread of equal size will have the same strength, using thread on an improper machine will result in interruptions to the sewing process. 

If you have any additional sewing thread application questions, please contact our product experts at Quality Thread & Notions.