So working on my new found project.... I cleaned off tons of dirt from the quick built wings. They were hanging in a barn and have had years of accumulated dust on them. I used maroon scotch brite pads and a stiff brush so as not scratch the spars. So after taking a close look at the spars, I noticed, where the dirt was, there is staining of the aluminum. I can pretty much scrub these areas with the scotch brite and get the stain off but I am not sure how much of the aluminum I am removing. I wanted to get opinions from those who know a lot more than me about aluminum and the integrity of these spars. After blowing or brushing the dust off, the spars felt rough. I ran the maroon scotch brite pad over these areas and it smooths it out. I can't catch any of these stained areas with a finger nail and I don't see any pitting. So...thoughts? I was thinking about expoxy priming them anyway.