I have quite a bit of rust on the body, which I believe is surface rust. Sanding by hand is going to get old real fast. It could take me years to sand the roof of the car (the whole thing is rusty, but it hasn't gone all the way through).

I have two questions:
a) What tools can I use to make the job of removing the rust easier? I bought a "rotary tool" and used a sand paper "bit" to remove the paint and rust from some areas, but even that goes slow. Would a hand sander work, and not damage the metal?

b) After sanding some areas, after all the rust appears to be gone, there's a dark discoloration in part of the metal. Is it rust, or a stain that the rust left? Should it be sanded off as well?


Thanks for the help

 

HI sordith-------ok

well i like to use a DA air sander with something between 80 to 100 grit paper-----------The DA is the appropiate tool that you should be using since it shall minimize deep scratches into the metal----------plus it will minimize the possibility of causing the metal to warp or become wavey(sp err)

now you said that you have already stripped certain areas and that their is a staining effect left in its place----------there are many products out there that are supposed to remove good old oxidation/rust--------but in all honesty their is only one true remover of rust---------ACID----------sulfuric or muriatic acid both will remove the rust from within the pitted metal(that is what is really causing the stain effect)-----just make sure if you choose to use acid to wear gloves, eye protection and clothes you don't mind ruining------------put the acid in a smaller container so you can brush on the acid to the entire roof area once you have it completely stripped-----------allow the acid to do its work---------muriatic acid takes a little longer than the sulfuric---but does not smell nearly as bad--------you may need to do multiple applications til you feel the acid has completely removed all the rust---------once you feel it is done make yourself a combination of water and baking soda solution----mix it up well and just pour it onto all the areas you used the acid-------this will neutralize the acid-----------rinse it off with water hose and than towel dry the bare metal--------you will than need to let it air dry in the sun-----------as soon as it is completely dry you will than re-sand all the bare metal to minimize surface rust after you used the water-------------get yourself some good metal-etching primer and prime the bare metal so you have a good base to work from and this will prevent future rusting til you have your Z painted

Just be careful when using Acid-------that is my only real caution------also make sure to use the acid sparingly so it will not run to areas that you did not plan to have the acid get to-------keep some extra towels to help keep the acid from getting to those area


Good luck

 

Hey Ghost------I went back and read what i posted and yes it did seem a little confusing---------first strip paint off to bare metal--------than use acid to remove remaining rust----------than dry----------than sand again----than prime with metal etching primer---------

Ok you asked what a DA is-----sorry about that too-------too used to being in the business we just call it a DA--------DA stands for Dual Action Sander--------basically this bad-boy spins around and while spinning it changes its pivot point so that it does not completely spin in a circle-------hope that helped

 

I have a few suggestions for Sordith

First, acid is a good way to remove rust, but muratic acid is not the way to go. Phosphoric acid is a weaker acid that is used in many rust-remover products, including naval jelly. Phosphoric acid works well because after the rust is dissolved, the iron in the steel converts to iron phosphate, and leave s a rust-inhibiting layer on the surface of the metal. A product containing zinc will leave zinc phosphate, which is an even better rust inhibitor. Even so, the area should be primed within 24 hours.

The dark stains under the rust are rusted metal, but they do not have to be removed to finish the car. Simply etch them with the acid just as you did the bare metal, rinse, dry, and them prime.

 

So I don't have to worry about the acid eating through the metal as well? Where can I get the acid, and should I try to protect my glass and other non metalic surfaces?