Is this corrosion?

[ShortSnorter]

I just pulled the plastic off after ~2 years and this was underneath:



There was a good bit of residual adhesive over the area that is ?streaked? but that came off with acetone. MEK had no effect either.

[designerX]

I'm guessing it qualifies as very slight surface corrosion. Hit it with a scotchbrite pad (just like you would if it had a mirror like finish) and continue building.

[JonJay]

Maybe a slight amount of oxidation, which is technically a type of corrosion but it looks more like residual offgasing from the plastic protective sheet. Take a solvent and see if it wipes off. Otherwise, a light polishing as already suggested will clean it right up.

[rightrudder]

Or leave it alone. Completely normal for the Alclad to form a light layer of oxide. If you're going to prime, then yeah, I'd hit it with a Scotchbrite.