Our aluminum siding was painted once very poorly. I don't know if it wasn't preped right, or it was the paint, or both. It is flacking badly. We were going to replace it, but since I lost my job, we were going to try re-painting it. I was going to D/A sand the flats (which are approx. 8") and sand the bottom edge with a foam sanding block. Not sure what paint to use so flacking doesn't occur again. We appreciate your help.