Scuffed up all H.S. parts using maroon scothbrite. I decided to scuff everything up before dimpling as it seems to be a better soultion to insure dimples get scuffed up on the ribs Found that resting my orbital sander on a scotchbrite pad made quick work on the skins. For the H.S. I have decided to scuff, dimple and then prime. I wiped everything down with acetone but switched to isopropyl alcohol towards the end. I will dimple all part and then a final wipedown before priming.