I never use plastic "
polish" to shine my pens after sanding, instead I use
polishing compounds.
Compounds or "
scratch removers" are designed to remove scratch and swirl marks left by sanding, using a finer polish does little to remove these scratch and swirl patterns.
I use Novus and they make three products; #3 Heavy scratch remover, #2 Fine scratch remover and finally #1 Plastic clean and shine.
Needless to say, after sanding I will usually start with #3 then #2 then off to the buffer. Depending on the material, often the Novus #3 and #2 are sufficient without buffing.
The only time I use the Novus #1 is to periodically polish the pens on display. It's anti-static so helps the pens from collecting dust while sitting on my display racks.
I save the car waxes for my cars and brasso for my brass.