How do I remove this parking-deck-drip stain from my car's paint and windshield?

January 18, 2008 9:57 AM

How can I get this parking-deck-drip-residue off of my car's paint and windshield?

Do you park in a parking deck regularly? Has it dripped on your car from its cement ceiling when it has rained? Has it left this faint whitish residue on your car? Have you found anything that will get it off of either glass or paint?

A guy at the carwash told me this stuff is not unusual for people in parking decks. He didn't know how to get it off though and didn't mention what it was, e.g. something leeching out of the cement, paint from the parking space stripes, etc. It's like it's some kind of mineral stain, faint and just a hair this side of transparent, just ever so slightly white, if anything.

I've tried all the normal kind of cleaners on it such as windex, car wash soap, even (if I remember) CLR (Calcium/Lime/Rust), at least on the windshield. I was afraid to try that on the paint.

WTF is this stuff and how can I get it off?

posted by Askr to home & garden (7 comments total)

To clarify, I didn't know where this stuff had come from. It's clearly a drip pattern, though. You can see that it dripped in a couple spots and flowed down from there, staining all the way. At home I park outside under open sky. Could've been from parking any other place, though, I guess. I asked a guy at the car wash about it and he asked me if I parked in a deck. So, maybe his diagnosis was right and maybe not, but he seemed to recognize it. So maybe a simpler way to ask the question is "I've got this seemingly permanent residue on my paint and windshield from something that dripped on it. What can I use to remove it?"
posted by Askr at 10:00 AM on January 18

Polishing compound takes it right out. You can get some at any auto parts store. It will also buff out light scratches in your finish. It should be safe for use on the windshield as well, but test it in a corner first.
posted by caddis at 10:11 AM on January 18

Polishing compound would work, but it works by taking a layer of the paint off. So be careful. I'm surprised CLR didn't take care of it, try other acids like phosphoric, oxalic, HCl or vinegar. DILUTED.
posted by gjc at 10:49 AM on January 18

Polishing compound doesnt remove layers or paint, it removes an extremely thin part of the clearcoat of your paint. (I polish my car 2x a year). Definately safer than using some form of acid.

However, the first thing you should use is a Clay Bar (no affiliation with seller).
posted by mphuie at 11:52 AM on January 18

Forgot to include- clay bars are commonly used to remove paint overspray, so it should do the trick. Don't be afraid to clay your windshield either.
posted by mphuie at 11:54 AM on January 18

Not if he's polishing the thing everytime the parking deck drips onto him, and not if the paint is insusceptible to the acid. We don't know his car even HAS clearcoat, and what's the difference anyway? Clear paint is still paint. That said, you win the tread with the clay bar suggestion. Good call!
posted by gjc at 4:32 PM on January 18

Polishing compounds come in different grades, like sandpaper. Some will rip your finish right off (OK that is an exaggeration but be careful with the stronger ones) and some are so delicate that it seems impossible to rub out a defect. You want to pick the right one and the folks at the auto parts store can steer you to the right place. The clay bar may work, but it looks a little too fine for this job, but perhaps not as these drippings come out very easily (even toothpaste might work). The key is to not park where you will be dripped on. Look over your car when you park. Is there a big joint between the concrete slabs directly overhead? That is a bad place to be in the rain in some parking decks.
posted by caddis at 9:14 PM on January 18