Stainless Medium Conductive Thread is thin, strong, smooth, and made completely of 316L stainless steel. Once you start working with this thread you'll quickly agree it is optimal for any wearables work.
Stainless Medium Conductive Thread is 3 ply, thicker than every day polyester or cotton thread but still thin enough to be sewn by hand in medium-eye needles. This may be sew-able by a sewing machine that can handle 'heavy' thread. Because it is strong and smooth, it’s ideal for any wearable/e-textile project. It also has fairly low resistivity, 10 ohms per foot so you can use it to drive LEDs and other electronic components that use under ~100mA.
Because it is made of stainless steel fibers, it will not oxidize like silver does: your projects will not 'stop working' because of oxidation after a few months and it is completely safe to wash.
Adafruit Web Site:
https://www.adafruit.com/products/641