The way you describe is the way I've seen Fidel do it. The only
problems I've had are with the safety tape getting brittle and flaking
off on one 6 or 8 foot section of the wing outboard of the actuator
fairing, and once when gas from the tank vent soaked the area behind the
vent. I no longer fill the tanks of the Stemme (30 gal) unless I'm
making a long ferry flight.

Dan
5J

On 3/11/21 1:22 PM, Mark Grubb wrote:
I have never sanded either surface. Only 1 debond in 30 years and that ship had been hard-waxed to the point that the gelcoat was impregnated with wax. I use the application technique described above: Slowly pull the Tesa backing away at a very acute angle, and stick the mylar down incrementally, beginning from one end.

I agree that mylars are not seals, they are aerodynamic fairings.