Originally Posted by 240M3SRT
Well things are worse than i thought. Some of the watermarks ARE etched into the clearcoat. The bodyshop guy said it should be wet sanded with 3000 grit and then buffed, and that its hard to tell how deeply its etched until he starts on it.
If you trust him I'd let him try an area and see how it comes up. 3000 grit is pretty darn mild really and, in skilled hands, shouldn't give you any concern at all. The Alpine Electronics project I was involved in during the holidays involved us wetsanding with grits as course as 800 but nothing finer than 2500. Even the 2500 was very rare with the vast majority of the sanding being done with 1000 or 1500 grit. Yes, it was custom paint with more clean than a factory paint job, but your guy is talking about 3000 grit - I've seen it done plenty of times with no ill effects whatsover. Ask if he'll do a small area and let you have a look at the results. Even if he can only minimize the appearance by 80~90% you may be more than happy with that.
By the way, if you're at all interested in pictures of this Alpine project take a look
HERE