Eric Greenwell wrote:

I've always used the mylar with the adhesive already in place (I'm
curious why JJ doesn't).
Hi Eric,
I used some Mylar provided by the factory with adhesive already in
place on the flaps on an ASW-20 and the heat inside the trailer caused
the mylar to peal off between the mylar and the adhesive. The Mylar
was slick and had not been roughened up. This brings up another point,
recommend control locks on control surfaces while in the trailer,
especially flaps that won't otherwise stay in neutral.

I believe the main purpose of adding Mylar is to reduce drag, but if
you want added control authority, one can think about the combination
of Mylar and zig-zag. I use it on most rudders, but be careful adding
zig-zag to the elevator. I did on my LS-7 and the stall was the mose
abrupt I have ever seen..................took off the zig-zag!
Cheers,
JJ