Mylar Adhesive "Best Practices"

For the benefit of the group, let's hear about what works for
re-attaching mylar.

I had an older generation sailplane that when I got it had fabric tape
for sealing the ailerons and elevator, but it was due for replacement so
the upgrade was to mylar. Removed the old tape and used acetone with
lots of elbow grease and paper towels to remove the gum residue from the
tape. We used "Tessa Tape" from W&W and applied that and prior to
removing the backing pressed it down onto the gelcoat very firmly. Then
we put the mylar onto that and pressed it down firmly again. Followed
that with the safety tape and no issues for 4 years.

With that said, I later bought a factory glider and within 1.5 years a
portion of mylar was coming up on a short stretch of aileron. I removed
the mylar, cleaned with acetone, followed the same procedure as above
and that section was again coming up about 1.5 years later.

The tessa tape is very sticky stuff. I did not scuff the mylar in
either case, but in the second case, the mylar was pulling up from the
tape, not the tape pulling up from the gelcoat.