I have read here that solder is indistinguishable
from aluminum when polished but haven’t had
any luck getting solder to flow or fill in. They
have never explained the process.
The aluminum repair rod they sell to fix holes in
soda cans doesn’t look the same when polished.
Its not just laying on the surface. It penetrates
enough that it requires you go deep to get past it
in my experience.
A "Boat House Repair" is one that done without having tools or the skills to do it properly.