CRD,

I use either Kevlar, Monocord, or 10 pound spiderwire braid (GSP).

All of them seem to work just fine, but I find that I cut less hair with the Monocord or Spiderwire. The straight Kevlar seems to slice right through if you aren't careful.

I avoid the Gudebrod 'rodwrapping' threads because they are too thick for me for this application.

Buddy