How to clean/prep metal w/ light rust for paint?

66coupe351

Founding Member
Aug 24, 2001
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Los Angeles, CA
I've got the front end of my car jacked up and disassembled, and while I was under there I thought it would be a good idea to do some clean up and paint for protective reasons. I'm looking to do this to protect the metal at this point rather than as a high quality restoration. I don't own an air compressor or paint gun, so I will probably have to use cans of spray paint - is that acceptable?

The lower parts of the under-side of the car have a good layer of grease/oil/grime, and the upper parts have some light surface rust. I scraped some of the lower grime off with a flat-blade screw driver and the metal underneath appears to be in great condition.

How should I go about cleaning and prepping all this for paint? Wire brush, de-greaser, sand paper? Is there anything special that needs to be done to the surface rust, or can it just be cleaned up(with a wire brush, etc) and primered?
 
I dont like to use wire wheels,they fling the wires out.Use a drill motor and a "hamburger pattie" disc,it looks like a hard scotch brite and cleans the metal pretty good.As far as primer and paint,use a good bare metal primer and use a semi gloss,it will hide whatever you dont clean that well,gloss will show everything and flat doesnt look clean.
 
Thanks for the pad suggestion. Picked up a 3M 'paint and rust remover' pad last night. It doesn't get into all the corners very well, but does a good job of removing the paint and gunk from the areas it can get in.

Is there any extra prep that should be done on the light rust areas? Seems I've heard of rust inhibitors or neutralizers, but not really sure what they are or when they should be used.
 
As far as a converter, we used something called "rust mort" made by sem. It's basically acid, so be careful with it. It takes 24 hours to "cure", but it does change the look of the rust visibly-it turns very dark, almost black-so you can tell it did something. I dont know much personally about longevity, but when I asked here about it, someone said they used it 4 years ago and have noticed not "growth" of the rust they sprayed. It also stinks like heck, so be ready to spray it and leave the area for a while! As far as rattle can paint, krylon has a rust preventative/converting paint (primer & top coat) that we've used on most of our small pieces, as well as some of the replaced metal, and ir sprays real nice-I especially like the looks of the semiflat black (even if it's not in an area you see too often).
 
66coupe351 said:
I've got the front end of my car jacked up and disassembled, and while I was under there I thought it would be a good idea to do some clean up and paint for protective reasons. I'm looking to do this to protect the metal at this point rather than as a high quality restoration. I don't own an air compressor or paint gun, so I will probably have to use cans of spray paint - is that acceptable?

The lower parts of the under-side of the car have a good layer of grease/oil/grime, and the upper parts have some light surface rust. I scraped some of the lower grime off with a flat-blade screw driver and the metal underneath appears to be in great condition.

How should I go about cleaning and prepping all this for paint? Wire brush, de-greaser, sand paper? Is there anything special that needs to be done to the surface rust, or can it just be cleaned up(with a wire brush, etc) and primered?
For rust removal, I use every implement of destruction I can get my hands on: Drill operated and hand held wire brushes and 3M pads, plus various dremel and drill operated grinding bits. I maintain a substantial collection of wire brushes in all shapes and sizes. Sure a wire flies off now and then, but I’ve already learned the hard way to always wear goggles (looking like a dork for a few hours sure beats looking like a pirate with an eye patch for a month - plus the eye doctor using a dremel-like tool to clean embedded crap out of my cornea is an experience I can do without repeating). I tend to avoid the twisted rope type wire brushes as they are too aggressive for most jobs.

For minor surface rust and grease/oil removal, I use a stiff scrubbing brush and Por15’s Marine Clean product. It's the best cleaner/degreaser I've found to date, plus since it's supplied as a concentrate, you control its dilution/strength.
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