1. Even the strongest nylon thread weakens considerably after two years on
the shelf.

Geez, I hope not, Wolfgang. .....

Think of all the poor Skydivers, using chutes with nylon shroud lines
that are much more than two years old!

A Postscript: I had lunch today with a skydiving friend. He said
ultraviolet light does degrade nylon, and there have been cases of
partial failure (none fatal that he knew of) for that reason.

So keep your thread in a drawer, guys.

vince