Auto body repair & detailing: body work, water intrusion, body filler

Question

1973 scout repaint 1973 scout,not mush body panels available,I welded in hand made panels,used dura glass over welds,then fiberglassed over that ,rough sanded that and then body filler to smooth finish,primed sanded,sealed and urithane painted and cleared.8 months later the outter areas of repairs looks like bubbles under paint.like moister comeing in from rear,thats inpossable .what could it be.please help,I wouldnt want that to happen to a freinds classic car.

Answer
Either one of your repair materials is failing or you have water intrusion into the repairs from cracking or poorly sealed patches (or poorly constructed- I know how hand made panels can be) You can get water in the vehicle every time you wash it- it looks like something you wash regularly. If you cheated, and just tried to fiberglass or duragalss a couple little rust pinholes- that will cause early failure. There is still rust growing, like cancer, on the back side of the panel where you can't see it. About all you can do is to have it professionally undercoated with parifin based undercoat- it's a tan color, not black. This will help, but if you cheated anywhere, or had poor welds or big gaps between your welds ( a common mistake- there thould be no gaps in the welds at the seams on patches- they need stited completely all the way around) Bill