Guys, I'm painting my son's daily driver. First attempt at metallic. My question has to do with scuffing 2k primer before paint. Car has been blocked, washed, and masked. In the past, if I were painting (NON Metallic) over regular build 2k primer, I would use a red Scotch-Brite pad to scratch the surface. Will the red pad be too rough for metallic, or do I have to use the fine gray pad ? I don't have a gray pad, and wanted to paint the car in the morning.