For example, what kind of sandpaper is used under what circumstances; Polish the putty with 60 mesh for the first time, 320 mesh for the second time, and 800 mesh for the third time: if you just polish the paint skin, then polish it with 1000 mesh sandpaper. If the brightness is not up after brushing, you can polish it evenly with 2000 mesh sandpaper, and then polish it with a polishing machine!