Tonight I scuffed the trim tab skins and spar with some 150 grit sandpaper. I did this where the foam ribs will be glued down, and along the trailing edge where the wedge will be taped into position. The scuffing helps the glue adhere to the metal.
I started by masking the areas I needed to scuff, then carefully scuffing with sandpaper. Because I had already primed the spar, I needed to remove the primer in the areas where the ribs will be glued to the spar. Just a small dab of acetone on a terry towel was enough to break down the primer. With a few careful wipes the primer was gone and I was able to scuff the spar.
I used some more acetone to clean the sanded areas, then removed the tape. Finally I dimpled all the remaining holes in the skins, and they are now ready for riveting and glueing.
