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I would personally just use soap and water and keep its natural patina. You can get acid washes specifically for marine aluminum hulls. These are probably better for thicker motor boat welded hulls but I am sure they would work. I have also seen some polished aluminum canoes. If you...
Here are a few pictures from the seller. Some pretty rough patches.
The canoe is about 1.5 hours from me. I am not sure I can make it out there for a few days.
Decent weather and some free time so I did a little cleaning on the Penobscot.
Lots of overspray on one side. I haven't decided how far I am going to take this restoration. I may just leave it for now. I haven't paddled this canoe yet.
https://www.facebook.com/share/zJVfwpJh9qgbGbWr/?mibextid=kL3p88
This is posted on marketplace locally. It looks like maybe a WW1? Anybody have experience or information on these?