2500 grit wetsand couldn't get this out...Ideas?

[Gray_Panther]

Hey everyone,



Just left my cousin's house where I tried my best to level out these defects on the hood of his BMW 325xi.

His father, my uncle, borrowed his car for a weekend and thought it would be nice to wash his car. Well he used an actual brillo pad to scrub to give it a good scrubbin'. And he scrubbed it hard. It's really bad as you can tell. I tried wetsanding with 2500 grit. And then compounded with a couple passes of Megs 105. It didn't even put a dent in it. I didn't even bother with after pictures. I was so disappointed.



What more can I do? The hood was gray and hazed when I got done wetsanding. After compounding it was shiny black again (It needed to be finished down, but we didn't bother since the scratches remained).



It looks really deep, is a repaint needed?



BTW, here is a claybar shot on a quarter of the hood...

 

[C. Charles Hahn]

2500 grit isn't (necessarily) really all that aggressive; you might not have been removing as much material as you thought you were.



That said, if it was scrubbed with a Brillo pad some of the scratches may very well be too deep to safely remove 100%.



So my questions would be:



1) How many section passes with 2500 grit did you make? Were you working in a circular pattern, straight lines, or cross-hatch?



2) What machine and pad were you using with 105? How many section passes?

 

[Gray_Panther]

2500 grit isn't (necessarily) really all that aggressive; you might not have been removing as much material as you thought you were.



I have 800 grit, but I left that at home thinking it would be too aggressive.



That said, if it was scrubbed with a Brillo pad some of the scratches may very well be too deep to safely remove 100%.



So my questions would be:



1) How many section passes with 2500 grit did you make? Were you working in a circular pattern, straight lines, or cross-hatch?



Straight line (Direction of wind flow), I am not sure what you mean by section passes. But I kept my passes even, wetsanded the whole hood 3x over. Still didn't even put a dent in it.



2) What machine and pad were you using with 105? How many section passes?

PC7424XP with Uber yellow cutting pad. I compounded the hood about 4 times. Each time after wetsanding, and then a final once over. Would a wool pad or MF cutting pad made that much more of a difference. At the time I didn't think so.



Note: There is still plenty of clearcoat left. I definitely didn't sand down to the paint. I put on some opti-coat for the hood to put a few microns of protection back on the paint.



Thanks for the reply.

 

[Accumulator]

Gray_Panther- Note that you can trash the paint by overthinning it *LONG* before you get anywhere near striking through the clear. Gotta be careful about this stuff and you haven't mentioned taking any paint thickness readings...



That said, some BMW clear is awfully hard (just as other BMW clear is awfully soft), and the 2500, at least the way you used it, might not have been aggressive enough for efficient (time-wise) correction. But I wouldn't jump all the way to 800 grit! 2000 can have a lot more cut than 2500, and if 1500 didn't do the job then IMO the job isn't safe to do period.

 

[Gray_Panther]

Gray_Panther- Note that you can trash the paint by overthinning it *LONG* before you get anywhere near striking through the clear. Gotta be careful about this stuff and you haven't mentioned taking any paint thickness readings...



That said, some BMW clear is awfully hard (just as other BMW clear is awfully soft), and the 2500, at least the way you used it, might not have been aggressive enough for efficient (time-wise) correction. But I wouldn't jump all the way to 800 grit! 2000 can have a lot more cut than 2500, and if 1500 didn't do the job then IMO the job isn't safe to do period.

The paint is Jet Black, isn't it the softest of its kind or am i confusing it with BSM? I don't have a paint depth meter, which is why I stopped so soon.

 

[Swanicyouth]

A little off topic, but you are sanding clear coat. How does the color underneath it affect how "hard" or "soft" it is.



I always though when people say BMW JB is so "soft" that the color just amplifies the lightest defect, not that that the clear coat on top of the JB base coat is any softer than BSM or any other color.



?

 

[Gray_Panther]

A little off topic, but you are sanding clear coat. How does the color underneath it affect how "hard" or "soft" it is.



I always though when people say BMW JB is so "soft" that the color just amplifies the lightest defect, not that that the clear coat on top of the JB base coat is any softer than BSM or any other color.



?

To clarify, it is the clearcoat. This is my first time hearing from Accumulator that BMW clearcoat can be hard. Even polishing my deep sea blue 1er i found the clearcoat to be extremely soft also.

 

[C. Charles Hahn]

A little off topic, but you are sanding clear coat. How does the color underneath it affect how "hard" or "soft" it is.



I always though when people say BMW JB is so "soft" that the color just amplifies the lightest defect, not that that the clear coat on top of the JB base coat is any softer than BSM or any other color.



?

With ANY manufacturer, there are a number of factors that go into whether the clear cures "hard" or "soft" -- and there can even be variance on a day-to-day basis.



As far as how the base color affects how hard or soft the clear is, it's important to remember that different base-coat colors have slight differences to their chemical makeup simply as a product of using different pigments, added micas for metallic colors, etc. and since the clear is applied during an "open" time, there is a bonding/reactionary relationship between the base and clear which can have an effect on how the paint system cures.

 

[Accumulator]

Gray_Panther- Yeah, the JB is generally said to be the soft one.



I'm no expert on this topic as I've never dealt with stupid-soft paint (nor will I...).



But FWIW, the only BMWs I've worked on were relatively hard. My e30 M3 was medium, but my e36 M3s were all very hard, the Byzanz Metallic one being probably the hardest clear I've ever worked on (and that's saying something given all my Audis and GMs). The e38 740 I did for a friend was also pretty hard, but not quite Audi-hard.



Thing is, if the one you're working on is very soft, then it oughta have all kinds of micromarring in addition to the "major marring" that you're trying to wetsand away.



And, again just FWIW, I don't like yellow cutting pads, *GREATLY* preferring either the Meguiar's burgundy foam cutting pads (either the old 7006 or the newer one) or, especially, their MF Cutting Disks (which have basically replaced foam and wool cutting pads for me).