I had this in the "paint" section but wasnt getting the response...(well the response I did get was well informative and I will accept their reply as if it was God himself) but I thought I would generate a more intuitive response here(meaning ...I am fixing to start asking more stupid questions..LOL.

OK...I started sanding my truck with 220....and it seems it goes straight to bare medal. Am I using to course of grit or is the paint just that thin?

 

80 grit to go to bare metal sanding.

300-400 for paint removal

800-1000 to smooth out the scratches from the sanding.

1000-2000 WET sanding to smooth everything out really nice before painting to get a nice foundation.

 

Your paint must be VERY thin or you are not keeping the sander flat.

Typically 36-80 is for stripping and rough body filler sculpting.
Then 220 is good for feather edging scratches and final body filler sanding.
400-600 is good for wet sanding after primer to smooth things out before paint
1000-2000 is for wet sanding the final paint in preparation for buffing.

You can take my words with a grain of salt, but I have worked in a body shop and have more than one 1st place show truck

 

are you changing the color or just hiding some bodywork? I use 600 grit just to remove the clear (2 stage paint) honestly re-clearing a vehicle makes it look new without removing the color (base)

 

Wow...I cant understand why that 220 goes straight to the metal; of course I can see the factory under(stuff) below...you know in each layer...I am no painter...can you tell...LOL

 

I used 180 in a good DA sander and it took the clear right off just perfect. I then went over with 320 to smooth things out and sme self etching primer to cover the metal until I get ready to prime the whole truck. When I get ready I will run over the whole thing again removing the self etching primer and shoot the whole truck with epoxy primer. For a really good finish you need to put a nice thick build on and stick sand it to get rid of imperfections.