Originally Posted by Warden Brown
Anyone know what causes this or what to do about it?
Yep. It's where the clearcoat was damaged (or removed?) previous to your Citristripping (probably years ago!?) and the bare aluminum has oxidized. The 'whiter' areas have been exposed to the elements longer than the 'grayer' areas. Think of it like a peeling sunburn...
If you are planning on polishing, you will be able to remove those splotches during the polishing process. Otherwise, now that you've stripped the aluminum, the rest of the trailer will oxidize & 'catch-up' to the oxidation level of the splotches in 10-20 years and it's be less noticeable.