It seem I have the same problem as TIFOSE came back from a ski-ing vacation and notice after washing my Black ML 320. I have what appears to be hard water stains on my black pinted plastic bumper. It looks like something eat or damaged the clear coat.

And I remember reading this tread a while ago.

I tried the obvious. Washing with soap and water, wd40, alcohol and dish washing soap (to remove the wax) nothing.

Something suggesting using mother's pre wax paint cleaner. My question is does that work on black paint? And how does the paint cleaner work anyways. Is that a polish. To me a polish is a fine abrasive.

Anyone had any success with a simular problem??

thanks
ben

Something suggesting using mother's pre wax paint cleaner. My question is does that work on black paint

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Silver Honda Accord, 2006
Silver G500, 2003
Silver SLK-320, 2002
Black ML-320, 2000
Bule Porsche 993 Targa , 1997
Silver Merkur XR4Ti, 1987