How do I know when I've sanded down far enough?

[brrymnvette]

Well, I spent an hour with the flap wheel. Tried to knock the surface rust off and here's where I'm at. Pics kinda suck b/c I'm using my iPhone has my camera. What should I use to fill in the pitting? How do I get the rust out of the pitting? Should I coat it with some POR-15?

All your tips and comments are welcome. This is my first attempt at real body work so I'm figuring it out as I go and from here.





These are the only spots that are rusted through, the rest of the panel is solid from what I've seen so far.




The quarter after I got all the surface rust off this section.




You can see where I stopped for the night. Have to give the wife some attention.