[gashalot]

I recently parked in the underground deck at my office, and returned to find a white residue had dripped over portions of my roof and hood. The closest thing I can think to compare it to is the calcium/lime deposits you might see on the surface of your shower if you have extremely hard water. That said, it's obviously not that, because this formed in a single day.

I washed the car again today, and most of it came off with a very vigorous scrubbing with my MF mitts and Mother's California Gold car wash, but some of the thicker area, especially around the fin, didn't want to budge (although I got a lot of it off).

I'm curious -- what's the harshest chemical / rub / mitt that you'd use on the clear coat? When dry, this residue is very white and extremely noticeable, so I'd like to get it off sooner rather than later.

Suggestions on how to remove are greatly appreciated!

[SpecC]

maybe you could try this procedure recommended to me by our local detailer

http://www.e90post.com/forums/showpo...1&postcount=24

[pander5]

If it's hard water spotting or garage concrete drip here's a method that might help.

Concrete Spots:
Calcified water spots on paint and glass, water and concrete spots are pretty much the same chemically - calcium carbonate, with the concrete being cross-linked with water

Methodology
•Apply 1:1 ratio water with distilled White Vinegar solution, and using a spray bottle, spray that mixture on the spots and let them "soak." Then rinse with water and repeat as necessary.
•If the ambient temperature water/vinegar mix does not work, warm (100-120 degrees) 100% distilled White Vinegar, saturate a clean kitchen sponge with pure vinegar and hold the sponge over the concrete spots for a few minutes.

•If the above do not remove them try equal parts distilled water, isopropyl alcohol and distilled white vinegar. The acid in the vinegar will help etch and dissolve the concrete.
•Rinse the area thoroughly with water after the vinegar and then reapply wax or sealant to that area.

[Gort]

I had some parking garage concrete juice (calcium, aluminum, silicate salts) on my G35 Coupe that resisted even the straight vinegar. I dabbed in with a rag saturated with "Lime-A-Way" and followed by wiping with a rag wet with just water. It worked with no damage to the paint.