Treating bubbling roof paint

[skoller]

My Defenders roof in a few spots has developed a few bubbling paint spots. Can anyone tell me if the aluminium has been treated eg anodised or something before it was painted. I dont know if I should be sanding it back to bright metal before I etch prime it or just give it a good clean. There doesn't appear to be any white corrosion powder so it has not yet corroded.

[VladTepes]

anodised? no.

I have the same issue on my bonnet. Will be sanding and repainting.

[rar110]

If it's a metallic colour it could be the clear rather than the base paint. If yes you need to sand it back which normally affects base and do both again.