Id say its about as stretchy as a high quality electrical tape but
about twice as thick.
It tends to want to return to its original length after stretching
unless you press it down against itself.
Once it has been terminated it remains stable, it doesnt seem to want
to unravel over time.
Both sides are identical so all termination requires is pressing the
end onto any part you have already applied.
I dont think applying dielectric grease before hand is a good idea, it
may liquefy if it gets hot and leach between the layers of tape
through capillary action, then the tape would lose its bond.
Its only a few bucks a roll but I would be more than happy to mail you
a sample if you want to check it out, you can send me your address
off-list if you like (garretsontech@xxxxxxxxx).
I personally cut all bolts and screws and grind them smooth so they
are even with or shorter than whatever they thread into.
I too have experienced similar anomalies as Shannon.
I use 12K trannys and I burned a carbon trace through the framework of
my coil from the MMC to the primary because the terminal of the cap
was less than an inch from the plywood.
It went through 8 horizontal inches of 5/8 plywood to get to the part
of the primary bent downward and through to attach to the spark gap.
The only thing that stopped it was a piece of silicon pot holder I cut
and stuck between the cap and the plywood.
I have since rebuilt the MMC and the terminals are now on the sides.
I also had a porcelain insulator explode because I used a steel screw
through it to hold up a strike rail.
It was close enough to the primary (still inside the insulator mind
you) that it didnt care what was in its path, it just blew a hole
right through it. There may have been moisture in it the porcelain but
I still couldnt believe it.
Regardless of whether or not 12 or 15 kilovolts is really "high
voltage", it can be surprising to see how it has a mind of its own.
I guess when you try to jam a whole bunch of stuff in a small package
thats just what happens.
Im completely rebuilding my coil because of issues like that and you
cant expect your first coil to be free of them.