Touch Up Paint not sticking to car

[Andrewiffic]

So I recently picked up this 2008 Black A4 and it has a few paintchips on it. Some are about the size of a dime. One on the driver's door and a couple on the pass. side. I used a paint touch-up bottle with a brush like I have many times in the past, but the paint didn't stay on after a day of driving. Bare metal is showing, so I lightly sanded the spot (maybe I need to sand it more?), applied the touch up paint till no metal was visible at all and allowed it to dry for at least 24hrs. Then after checking it a couple days later it was gone as if I never did anything.

I think I read somewhere that Audi uses galvanized or zinc-coated steel for their bodies. Is that why the paint isn't adhering? Do I need to sand it more, prime it first? Or both? I don't like leaving these bare metal chips because I'm worried about it rusting.

[shahk62]

Prime first then touch up. Ideally you'd want to be sanding down, spray priming and spray painting rather than using a touch up kit.


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[ECS Tuning-Audi]

Unfortunately a paint flake the size of a dime isn't going to be able to be touched up with a small brush kit. Likely need to prep, prime, paint/blend/clear a small area.

Jason

[Guitarmageddon]

So I recently picked up this 2008 Black A4 and it has a few paintchips on it. Some are about the size of a dime. One on the driver's door and a couple on the pass. side. I used a paint touch-up bottle with a brush like I have many times in the past, but the paint didn't stay on after a day of driving. Bare metal is showing, so I lightly sanded the spot (maybe I need to sand it more?), applied the touch up paint till no metal was visible at all and allowed it to dry for at least 24hrs. Then after checking it a couple days later it was gone as if I never did anything.

I think I read somewhere that Audi uses galvanized or zinc-coated steel for their bodies. Is that why the paint isn't adhering? Do I need to sand it more, prime it first? Or both? I don't like leaving these bare metal chips because I'm worried about it rusting.

I just used Dr Color chip on the jetta and its held up just fine. Where did you get your paint from?

[mtroxel]

Maybe a dumb question, but you do this in a warm garage didn't you?

[Andrewiffic]

I just used Dr Color chip on the jetta and its held up just fine. Where did you get your paint from?

I bought it from Canadian Tire. It's worked on my previous cars without issue.

Maybe a dumb question, but you do this in a warm garage didn't you?

Yup, warm garage.

I guess I'll have to try sanding it down, priming, then painting. I'm just worried about causing rust because it's exposed right now and not rusting at all so Audi must have some sort of coating on the metal.

[mtroxel]

I'm just worried about causing rust because it's exposed right now and not rusting at all so Audi must have some sort of coating on the metal.

They're galvanized. Rust is not impossible, but a little scratch is much less likely to rust.

[08 classic]

Well if its zinc and has been exposed for too long, zinc oxidizes creating white rust which is a contaminant. Sanding will remove it but after sanding, wipe it with some thinner to remove dust, and oils. If you went to bare metal re-apply primer, if still has primer then just touch up. Keep an eye on the surface temp and air temperature follow material instructions for applications, and also add clear.

Hope this helps you...