Black blotches

[atvmcg]

I was away with work for 6 months, and on return I notice I have a series of black blotches. Any ideas as to why?
I was parked under a tree, but the blotch areas are sporadic.
Thanks.

[AWCHIEF]

Sounds like Filiform corrosion. The curse of Airstream owners.

[atvmcg]

Thanks. I'm not familiar with that term. Could you expound on that? Would an all over polish job correct it?

[rodsterinfl]

Sounds like some sort of tree dropping. Figure out if it is in one area, just over the top and top sides, etc. It could be sap, some saps are not syrup-like. It could also be bug related. Try a bug off or tar remover for autos.

My filiform began as white not black.

[atvmcg]

Just tried a bug/tar remover. Seem like it took some of the residue off with the usual work in. I'll reapply tomorrow. Thanks. I do have a feeling it's a tree sap problem.

[barts]

Filliform is white.

Search for aluminum filliform corrosion on google image search for examples.

- Bart