[dsraven]

great article Brian. I learned the same tecnique by trial and error. I also learned that a block sander with foam under the sandpaper can make more work for you if not used properly. when I was learning (self taught trial and error) back yard bodywork I would press too hard on the foam backed sander which would distort the panel from too much pressure and also the foam would conform to the wrong shape. now I use a hard block. actually I use a piece of plywood with the sandpaper stapled onto it. along with that i use light pressure. that way only the high spots get sanded off. longer board equals flatter surface. keep the sandpaper tight on the board as well.

I know, rocket science, right?

in the end, after I think I am ready for paint, what has worked for me is to put a light at the front or rear of the vehicle, then wipe the whole thing down liberally with a dripping wet rag of wax and grease remover, then stand at the other end and look down the vehicle. if you see ripples or bumps etc then that is what the new paint job will also reveal. if you like what you see then you are ready for the final prep. if not you have more work to do.