It's a rainy, dreary day here in SE PA, so no trouting for me. But
the 2 threads (pun) on leader boiling provided me some jollies.

I don't want to add fuel to the fire (not taking sides on boiling
water for leaders, tea or underwear - Fruite de la Loome?), but I
wanted to add some technical information gleaned from 4 semi-fun years
at a technical institution in New England and that many decades at the
company that invented nylon and a few other miracles of science.

There's plenty of room for members having a variety of experiences,
since there are a lot more just one nylon. There are also
copolymers. I've also run into tippets that had a coating over a
core. We'll save discussion on fluorocarbons for another time/

The members seem to have good knowledge about melting points. But
thermoplastics, including nylon, have another yet undiscussed
characteristic: the second order thermodynamic property, glass
transition temperature. This is the point below which polymers act
like a glass and above which they become rubbery.

Other distinguishing factors with nylon (besides the obvious ones of
composition) are molecular weight, MW distribution, cross linking
density (if any), thermal history - such as with dyeing, dynamic
history - how stretched it was as it was spun and drawn, inherent
moisture content.

Nylons don't oxidize as readily as some other polymers, but they are
subject to degradation. High energy EMF (Gamma irradiates their
tippet and tennis string) and UV light, as well as free radical attack
will change the tippet properties (possibly for the better). Over
time, low molecular, lightly bound entities which might function as
plasticizers will be fugititve, and you might find your tippet getting
stiffer and less elastic (not the same things) with age.

One parting thought - those of you boiling eggs or leaders at high
altitudes will find your temperatures slightly different. It makes a
difference for me with soft boiled eggs and tea - dunno yet about
leaders.

tl
les