Specific Sandpaper Models That 4S Shops&Repair Shops Use

4S shops and repair shops use clean dry grinding system that generally needs dry abrasive papers with eight granularity sizes. They are respectively 80# sandpaper, 120# sandpaper, 180# sandpaper, 240# sandpaper, 320# sandpaper, 400# sandpaper, 500# sandpaper and 600# sandpaper. Many sandpaper suppliers at iAbrasive.com can supply these sandpaper models.

Firstly, 120# sandpaper can grind out the feather edge, whose standard is 3cm. When automobil putty becomes dry, please use carbon powder served with 80#, 120#, 180# dry sandpaper.

It only requires the smoothness for the first grinding. After grinding with 80# sandpaper, please use carbon powder before changing grain sizes of sandpaper, and then you will see that the rough sandpaper marks left from the previous grinding. It doesn't matter, please continue to change 180#. 180# sandpaper mainly is to eliminate the previous sandpaper marks, and the carbon powder can be polished away.

If automobil putty has grinded out a smooth surface, next please change 400# sandpaper and expand the grinding area for the next spray paint work. Please note that it must be totally dry.

The carbon powder should be used firstly before polishing primer and then use 400# sandpaper directly to polish the entire panel until all is smooth. It is best not to use wet sanding. 

PS: 400# dry sandpaper is suitable for one-component paint, and 500# and 600# sandpaper are suitable for double process, three processes of metallic paint and pearl paint.