It may depend on who/where you get them from. In addition to using string quality gut for frets, I have sometimes used so-called fret gut for strings- so far no false or weak ones. Nylon frets are an abomination- they are a royal pain to tie, (slippery as hell) they don't like to lie flat near the fingerboard edge, and they sound horrible. I can't give a reason why this is so, but such has always been my perception. I would much rather use nylon strings with gut frets than vice versa.
Dan > Anybody could tell the difference between a fret gut and a normal gut > string? Are they of the same quality? -- To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
