S and Z Twists Continued

During yesterday’s class, there was a question about S-twist and Z-twist yarns and why one-ply yarns often are spun in one direction and when turned into two-ply yarns are spun in the opposite direction. I gave a simple answer of because it prevents unraveling, but here is a better visual explanation why, as explained by the Khipu Database Project.

Illustration by Julia Meyerson. From the Khipu Database Project.

A certain amount of twist is needed to hold the fibers together. Twist over that amount resides in the thread in the form of energy. A freshly spun singles thread almost always has extra energy, which makes the yarn want to kink back on itself and form snarls. One way to counteract this is to ply two yarns with the same twist together in the direction opposite that in which they were originally spun. That is, two S-yarns would be spun together in the Z direction; this operation is called plying, and each S-yarn is called a ply. The Z-twist of the plying operation holds the two yarns together and balances out the S-twist in the singles so that the finished yarn is stable and has no tendency to kink or snarl.

From: http://khipukamayuq.fas.harvard.edu/KhipuConstructCords.html

Assignment 2: Beginners’ Sewing and Embroidery for Circuits

Assignment 2 – Individual


  • 3 * 1.5 Coin Cell Batteries
  • 1 Coin Cell Holder
  • 1 Pushbutton Switch
  • 1 LED
  • 1 * 220 ohm resistor
  • 12” of Conductive Thread
  • 1 Spool of regular thread
  • Wires


  • 1 Multimeter
  • Sewing Needle
  • Embroidery Hoop

Your challenge in this assignment is to make a version of the circuit you made on the breadboard on a piece of fabric. Practice sewing on fabric first before jumping onto your fabric circuit.

  1. Outline where all the materials need to be placed and check the circuits to make sure they work in the arrangement you decide on.

  2. Sew the materials in place with regular thread using the couching method.

  3. Sew the connections together with conductive thread.

  4. If you have time, try thinking of different ways of replacing the pushbutton switch with means of closing a circuit.

Here are some great examples from students of previous semesters:

Maya’s light-up choker

Jiayi’s Circuit

Ariel’s Circuit

Konrad’s Circuit

Assignment 1 – Felting + Simple Circuits

Assignment 1 – Felting + Simple Circuits


  • 1 Handful of wool roving.
  • 1 Coin cell battery
  • 1 LED
  • Vinyl Tape


  • Felting needles.
  • Styrofoam block
  • Scissors

Your challenge this assignment is to create a piece of fabric that you felted yourself and incorporate circuitry onto it. One example is to create a soft switch for a 3 volt coin-cell battery to power up an LED.

Felt two pieces of fabric together, forming a pocket for the battery.

Make a hole in one of the sides of the pockets for an LED lead to be able to touch.

Tape down the long lead of the LED to the battery’s positive side, and leave the short lead outside of the pocket. Make sure you are not short circuiting the battery.

When you press down on the felt pocket, it should light up your LED.

Take photos and notes throughout the experience for documentation. We will go over posting your experience on the documentation blog next week. This is an individual assignment. Each person must create their own fabric and document their own work.