1. The first choice is to hang putty with a big ruler, and hang it over and over again, but it is not thick enough. Generally, a large ruler is used to flatten the pit. First, hang the pit there, then flatten the whole pit with a large ruler. After leveling, hang the line separately, and then use fine ones for rough grinding.

2. After polishing, touch it carefully, then sit down and mark the pit, fill the marked ground with a big ruler, then make the whole super flat with a big ruler, and then hang the line separately. This time, it must be super thick and the putty must be thick enough, and then rough grinding is used, because the sandpaper is too thin to polish the uneven putty.

3. Don't put the rough grinding in place at once, leave some putty for fine grinding, and the sandpaper used for fine grinding is between 120-240. If possible, it can be finely ground and then coated with a layer of toner indicating layer; If not, you can scrape the eye ash, which must be very thin, and then polish it with 320 sandpaper. In this step, in order to minimize the traces of sandpaper, you are afraid that the traces of sandpaper will be too heavy when spraying primer, or it will come out later.