I figured painting just the roof first would be a good test of my ability to spray a decent black paintjob. Here is the roof stripped of all the loose paint, leaving behind the still-good factory primer. The remaining white areas were where the paint was shielded from the sun under the light bar and under the car's number decals. This was a cool find because Santa Barbara County had removed these roof numbers before sending the car to auction. Judging by the shapes, mine was car 418. This remaining paint still had a strong bond to the primer, so there was no need to sand it all off. Just be sure to sand the transition between the primer and the paint. This technique is known as featheredge sanding and it removes the ridge between the primer and the paint on top of it. To do this, I used 220-grit on a DA followed by 400 on a sanding block, sanding until I could no longer feel a difference between where the paint stopped and started. Once masked, blow the surface with compressed air and wipe with degreaser.