Rust repair
Work continues on the junkyard donor door someone installed along the way. We were prepping it for body and paint and noticed a tiny bubble in the front lower corner.
Turned out to be rust cancer starting to form. This is the first we found on the car but not too surprising since the origins of the door is unknown. Dirt and water gets trapped in some recess on the inside and then cancer forms - it literally rusts from the inside, out.
The cure is to cut it out and weld fresh metal back in it's place. If you just paint over it, the rust will continue to spread and the new paint will eventually just bubble up and fail.