Many years ago, I was taught some elementary "Survival Sewing for Military Men" by a gruff Chief Boatswain's Mate. Said Chief insisted that the one true and proper thread for virtually any repair was "Buttonhole Twist" which, being twisted from two yarns of silk, was sturdier than virtually any other thread of similar diameter. I imagine that the twist, resembling naval cordage, appealed to his aesthetic sensibilities as well.

Over the years I have replaced innumerable buttons with this stuff and can honestly say that I never recall losing one that had been sewn on with "twist." I've also used it to repair rents in various articles, do an emergency trouser hem and the like. Never had cause to complain of the outcome.

Downside: It is pricy and hard to find. Being twisted, it is subject to tangling unless you keep some light tension on it. Also, I have learned to have a sharp knife or scissor available to cut it, as trying to break the stuff manually is doomed to failure and is liable to result in a nasty cut.

Has anyone else ever used this stuff? If so, what for?