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

[brrymnvette]

Just spent about 20 min doing a little test piece to see if it would be easy to see when I got down far enough. As you can see, the car is Maroon and it's a little hard to tell. I used 80 grit on most of it, and 40 grit on a small section to see if I could see the bare metal easier.

Any tips you have are appreciated.

[67 ls1 vert]

80 grit is way to coarse if you plan on spraying as is. Tell us a little about your goals and what color you plan on painting it. Are you going for a simple repaint or a nice straight body with a dark color?

[brrymnvette]

Very simple repaint with a blue color. Not going to be a show car by any means. Just a dd that I'm throwing together.

[67 ls1 vert]

If the paint isn't checked or cracked and looks pretty good except for being old or faded, just sand it with 600 and do it again with 800 wet. Remove as much as you can from the car makes it much easier. Chrome, SS trim around windows, window felts, any emblems, etc...

No need to take it to metal if you have a solid base. Make sure you get everything sanded smooth.

[brrymnvette]

It's pretty much all surface rust. Like if you just rub your hand over the paint it feels like 800 grit already and your hand is brown.

[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.

[Denvervet]

I'm sure some experts will chime in here but I can't imagine any paint will stay adhered to that rust for any length of time. Pitting? means this is more than surface rust and will grow under any coating you put on it. Media blast ...........though I know it's more than you are looking to get into.

[JRouche]

Well?? Till its shiny.. I used 80 grit for the entire thing.





But in your case I would not!! Sand it down till you are removing the old paint and rust but NO metal. You dont want to dish the panels. Just remove the stuff that is not metal to the surface of the metal. When you hit shiny metal STOP. Dont try to remove the pits or deep rust....

Then its simple. I get your use, its a DD, not a show car. The best product that I have used for body panels and rust is Must for Rust. Google it and get a gallon. POR is great for frame work. But for body panels its too thick. It will be seen as a gloppy paint job when the final paint is applied.

The must for rust converts the rust and doesnt add any thickness that will show up on the final paint job. And it converts it fast and perfectly. I use a scotch bright pad to apply it along with a spray bottle. Just rub it in, wipe off the excess and let it sit for a day.

For deeper pits I like to use a wire brush, not a wire wheel, a hand brush, a soft one, fine wires so it will push the MFR into the pits. And make sure the body is clean of any grease or oil. Acid doesnt penetrate oil. An acetone wash of the panel before the acid treatment works best...

After the use of MFR I just dry scrub the panel with a scotch bright pad to remove any loose particles. On heavy rust you may need to repeat...

Wash with wax and grease remover and prime. I like epoxy primer.. Etching primer might sound good for the rust but the pits will hold some active acid and cause some real issues later. JR

[brrymnvette]

Thanks for the replies guys.


Looking up Must for Rust now.