I sand the area where the stickie will go with 200 grit and sand the inside (10mm) of the Mylar with 200 grit also. Then wipe everything down with Acetone.........it won't hurt Poly Urethane. Mask off the area to insure the Mylar goes on straight, then roll it down with lots of pressure. I use a 1" bearing on a stick.
JJ