they have white as well 
LOL 100% cotton with color
25' for $1.50
http://shop.yoyoexpert.com/product/287/5-Pack---100%-COTTON---YoYoExpert-String
Dan
, Is watch the heat. make sure you don't put to much voltage to the cotton wick or it will scorch.
I didn't LOL. The results so far seem to be with the SS mesh wrapped around the cotton it really takes higher voltage (1.2 ohms @ 4.6 volts and almost 18 watts after some juice buildup) without scorching the cotton. The SS must be dissipating the heat.


