Originally Posted by 66replica
I replaced an endcap segment with one of the new Airstream segments. Unfortunately, these segments are made of the new aluminum that Airstream is using while the rest of my trailer is 2024t3 Alclad.
Does that sound reasonable?
Unfortunately, it's not just the texture
of the new panels that are mismatched - that would be able to be resolved with sanding as you are considering.
The aluminum is a different alloy (chemical composition) so no, they will never "match". The Alclad has a purer aluminum coating on the vintage panel which polishes up much brighter than the new panel ever will. Even if polished, the new panel will have a different color - like pewter vs real silver...it'll be a darker grey.
A "darker grey" cloud effect can also be seen when a vintage panel is over polished and the Alclad layer is burned through or worn away. It isn't really noticeable when it is freshly polished - only after it has begun to oxidize a bit. It can show up in as little as a couple of days with exposure to the elements.