These pics are of my hood and roof; what would be the best steps to sand it to ensure that the rust is gone prior to priming and paint? I’m assuming sanding then a rust inhibitor, but what grit paper, etc.

 

You'll want to treat that with an acid to kill the rust before you put anything over it

 

Before sanding or anything? What kind of acid? Sorry if it’s basic stuff, I’ve always turned the wrenches, never messed with making them look better.

 

That looks more like full on pitting. By the time you remove the corrosion, the metal is going to be thinned and weakened. Just from what pitting the photo shows in the roof skin, I'd probably be looking for a donor skin to cut/weld into the car. Otherwise, you can chemically treat the rust, scrub as much away as possible and try to bury that moonscape under filler and sealers, but it'll probably come back as rust, or in some other way come back thru the new finish like a bad memory.

 

+ 1

Start sanding only after several iterations of chemical treatment to remove as much of that crap as possible BEFORE you start sanding. Like Drew said,... if you start off sanding first your not going to have much roof left by the time the rust is gone.

 

With only the posted pic to go by, the roof panel looks like it's too far gone to repair; by the time such deep rust is removed---if there aren't pinholes---what metal is left will be so thin it will 'oil-can.' I don't know what the rest of the car looks like, but if it's worth saving, you'll probably have to replace the roof with one from a salvage vehicle.


Don't attempt to just skim the panel with filler; every trace of rust must be removed before painting. Otherwise, the filler will lift, and bubbles will begin to appear under the new paint.

 

Thanks for the info. If roof needs replaced this may be a game changer. The car is in really good condition underneath, really just needs an interior and cleaned up but looks like maybe I underestimated the damage to the roof. Thanks again.

 

You could try covering it up with something like POR15, and do a quickie paint job. Or neutralize what you can with Ospho or a similar rust dissolver/cleaner. Some clever application of Evapo-Rust might work pretty well at removing and converting what you've got without etching the rest of the steel. A couple old towels soaked in Evapo-Rust, lay over the mess, stretch plastic over the towels so it can't evaporate, weigh it all down overnight, peel off the next day and repeat as necessary until you have clean pitted steel. Then prep, epoxy prime, body filler the pits, block sand, prime, block sand, prime, block sand, seal and paint.

Trouble with rust treatment, is you can convert the top rust, and have live rust underneath that you cant see until you sand the converted oxide off the top. Theoretically if the surface is converted and the rust underneath is sealed from oxygen, it won't grow back. But often it doesn't seem to work like that. Safest way is to remove the rust completely, within reason. But honestly there are a lot of cars at the local car show that have rust in them, you just can't see it, or it's been recently covered up. You might get a few years out of painting over some of the less serious rust before it gets bad enough to show through the finish again. Especially if the car is kept indoors.

 

Never seen it rusted there like that before.

 

yeah that looks more than surface. Might want to take the headliner off and see what it looks like from underneath. Given how pitted it is i'd be inclined to start with a wire wheel attachment for a drill, clean it all up, then let some phosphoric acid soak on that, and move on to some rough grit sandpaper. Finish up with another round of phosphoric acid. POR15 has worked for me - can be keyed up and painted over

 

All I got to say is get a gas mask, a good one!

 

Wow! The only car roofs I have ever seen with rust that bad are those that originally had a vinyl top, which obviously thirdgens never had.
Was that car fished out of a lake or something? 'Really have to wonder where else there is major rot. 'Looks like a lost cause to me...