Use 1000 grit sandpaper first then continue with 1500 grit sandpaper

proper sanding is done by sanding the case with soap water. it is to clean up the dirt or oil on your casing.

if u want to do a flat black paint job, i sugget getting Anchor® brand flat black, this is a heavy duty flat black can spray.

spray a thin layer 1st, let it dry. then do a 2nd coat & do a multiple layer for a better result, but remember to leat each coat to dry 1st...

then it is DONE...u'll get a durable heavy duty paint job for your case...