Because you don't, despite advice on flattening basecoat on here, don't do it. Which begs the question....is your initial coat basecoat? as I've never known a basecoat to have a peel to the finish. If it's a solid colour, then just flatten and polish that, no need for clearcoat. If you flatten your clearcoat and break through to the basecoat, you've gone wrong and will need to spot repair it or re-coat the panel. 1200 is too coarse for final finishing too. It's fine for sanding pre painting. If you are going to use 1200, go over it with 2500 to remove the scratches before polishing.
