I just wanted to mention that soldering irons come with different power ratings, 15 and 30 watts being most common, although they can have higher ratings than 30 watts. The lower the rating the less hot the tip of the iron gets, so maybe that explains the different results. Perhaps a 15 watt iron isn't sufficient for fret gut, especially the thicker frets.
morgan -- To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
