Originally Posted by Old Fool
Apparently the OP does not want to tell how he prepped and painted the car to figure the problem out.
Doesn't look like he even returned to the post?
He could shave the surface off and see what is under there, a careful shave cut and one of those fake bullet hole stickers and he would be set
My hunch is acid wash primer or similar as the original cause. But I am not a gambling man, so I wouldn't put any money on my hunch,LOL.
I'm thinking a drop of sweat landed on the bare metal, no wax & grease remover,along with thick material...or an air bubble in the filler...If it was moisture there would be lots of tiny bubbles not a big one here and there. Its anyones guess...it looks like a lot of time went into it though...
Mabee the OP used lacquer primer..and was too embarresed to come back...