Have you tried using denatured alcohol after scraping? I've found it helps clean off any sneaky silicone residue that's left behind. Might save you from having to scrape quite so obsessively...
Does denatured alcohol really get through silicone residue that well? I've always been skeptical, because silicone seems to cling like crazy. Last time I dealt with flashing, I ended up using mineral spirits instead—it worked okay-ish, but still felt like I was scraping forever. Maybe denatured alcohol is the trick I've been missing... worth a shot next time around, I guess. Have you noticed if it affects the aluminum finish at all?
I've had pretty good luck with denatured alcohol myself. Silicone residue is stubborn stuff, but the alcohol seems to break it down better than mineral spirits in my experience. Still takes some elbow grease though... nothing's ever easy, right? Haven't noticed any damage or discoloration on aluminum finishes either, so you should be safe there. Worth giving it a try next time—might save you some scraping frustration.
"Still takes some elbow grease though... nothing's ever easy, right?"
Haha, you're telling me. I've wrestled with silicone residue more times than I'd like to admit. Denatured alcohol does work pretty well, but honestly, sometimes I just cave and replace the flashing altogether—less frustration, more peace of mind.
I've been there too—spent a whole afternoon scraping silicone off flashing only to end up denting the aluminum beneath. Lesson learned: sometimes it's quicker (and safer for my sanity...) to just bite the bullet and replace it.
