Semi-Insulated Conductive Yarn
This yarn consists of 2 components: conductive core consisting of 3 single-ply z-twist yarns braided (yarn labeled "bad" from the lab), with 5 loops of 3-ply cotton S-twist yarn.
The "bad" conductive yarn, despite its excellent conductivity is difficult to sew with and often breaks since the stray fibers tend to catch on each other and surrounding materials. By using this yarn as the conductive core, risk of breakage and attachment to unintended materials is minimized. The resulting yarn is far too thick for sewing, though may be a useful edging/cording material. It is mostly shielded by the cotton, yet the conductive sections are also accessible for attachment to other electronic elements.
The process was adapted from the "5 sided braid" friendship bracelet - though it was a bit more difficult than intended to keep the conductive core in the center, you can see the modified interlacing method here: http://www.youtube.com/watch?v=3kWQNyQxKl4
Magnified views of the yarn show the conductive yarn surrounded by cotton yarns in the "5 sided braid" structure.
Conductivity 1.5 Ohm/inch Thickness 3/16/inch