Painting an auto scratch

In My Humble Opinion
1

I bought a 2008 Ranger at a good price; it has a 1/4" scratch running across half of the passenger side.
I will paint it with enamel, but how do I remove the rust that has accumulated in the scratch?

2

How deep is the scratch, and how bad is the rust?

3

The scratch is from the surface to 1/4" inch, a dent in places. It was clean when I bought it a week ago and has turned rusty again.

4

I have restored two cars & dealt with a lot of rust removal. It is critical to remove it all, even microscopic bits of rust will cause rusting under the new paint. This means that you either sand it down to bare metal (wire brushing won’t get it all) or use a wire brush followed by chemical removal.

You can use acid based products like Naval Jelly that converts the rust to iron phosphate or use a chelation approach with Metal Rescue which actually removes the rust, leaving unoxidized metal.

I have had the most success with the latter, but it requires several hours of immersion or constant contact with the rust. For a scratch, you have to get creative. Depending on the scratch, I would try build a trough of modeling clay or use strips of plastic & sponge held on with duct tape. Then pour in the Metal Rescue to fill the trough or keep the sponge saturated.

Then paint immediately.

5

Thanks!

6

Much to my surprise this stuff called Evapo-Rustavailable at Harbor Freight does a great job. My son told me about it. You have to keep the rust wet with the liquid so you would have to tape some cloth or paper towel soaked in it over the scratch on a vertical surface. But it gets down to bare metal pretty quickly.

ETA: Looking for some info I see this is aselective chelation agentthat is supposed to bind only to iron oxide.

7

For small scratches in/around dents I have had luck using a combination of an emery board and 400-grit steel wool on a popsicle stick. For me its always gotten things to clean metal without making/taking too much of the other areas away.

8

Metal Rescue is also removes rust via chelation. IME, chelation is much better than the phosphoric acid (Naval Jelly) products.