Clear Coat Pitting

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philh

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Hello - My first post on the forum but passionate about detailing. Have learned a ton from Mike and the detailing experts on this forum.

So here's my issue.
Working on an old 2001 BMW 540 with Sapphire Black Metallic paint. The car was parked outdoors for 14 years and was used as a daily driver (180K miles). I've been busy rebuilding/restoring the car back to how it was when I picked it up in Munich many years ago.

While compounding/polishing the hood with my Rupes Bigfoot 15 (Starting first with the Blue micro-fiber cutting pad) I noticed thousands of tiny craters in the surface that appear to be environmental damage from years of rain/sun cycles etching the clear, or possibly the clear coat is simply degenerating. I noticed the same problem on the roof, but not on the trunk lid - possibly because the trunk received more attention (and wax) over the life of the vehicle.

So, thought I could remove these with something more aggressive than a Rupes and tried wet-sanded lightly with 2000 grit. I didn't goo too far and decided to stop since I didn't have a paint thickness meter and didn't want to go too far and end up past the point of no return. The surface is now extremely smooth, but the little pinholes are still visible - maybe even more visible because all the other imperfections are gone.

I took a high-res pic to better see the imperfections in the paint. In person it doesn't look like this bad to the naked eye, but wanted to illustrate what was going on.
(Light/dark transition magnifies issue).
Pitting_1.jpg



So, here are my questions:
1. Is this typical Clear Coat pitting from environmental damage?
2. Can it be removed by more aggressive wet sanding?
3. Any other suggestions other than repainting?

Thanks!
 
Yes, I would say that's typical from sitting outside for 14 years. That could be from anything, from acid rain to bird droppings to tree sap to rail/brake dust etc.

I think you've done the best you can and I'd just live with it, more sanding or aggressive compounding is likely to just compromise the paint on a car you seem to be attached to. If you aren't bothered by repainting, then you can certainly go aggressive hoping to fix it and if it backfires, simply fall back on a repaint.

My two cents.
 
Is there anywhere on the car where the spots are most concentrated? I'm asking because on my car I have those on the front (mainly the hood) and I almost think of them as little "dents" in the paint from debris being thrown up by the cars in front of you.

Just do what I do ... polish the car so well it's too shiny to look at closely :laughing:
 
It is pitting, the car is old and used. I would not chase these, because you will end up chasing right thru the paint. Polish the car to bring back the shine, protect it and be on with it.

HUMP
 
Thanks for the feedback and initial "diagnosis" of "old paint". I might get the hood repainted because there are a lot of chips on the leading edge. Before I do that, I will try to wet sand a small area to see if they are shallow enough to remove - and report back. It is so tempting because they are barely visible and give the impression they could be removed through light sanding/compounding/polishing. But it may be an exercise in futility. Wish I had a paint thickness gauge.

Keep in mind the picture is magnified from a high resolution pic. Thought it would be easier to diagnose.
The entire hood is evenly covered with zillions of these micro-dots - almost like tiny pinholes and barely visible. But at the right angle they are visible and annoying to see. I'm trying not to mess with it anymore, but not sure I can leave well enough alone. Might need counseling.

Here's another pic, much different lighting, different angle, different section - also very magnified.
Pitting_2.jpg
 
Again, that is just from environmental contaminants sitting on the paint for too long. Tree stuff, bird stuff, pollution stuff, etc.

It's probably too deep to sand out, but if you're going to repaint the hood anyway...
 
my 99 black 540 looks exactly like that on the hood and roof, trunk lid mysteriously doesn't have that defect.
 
Why did your trunk lid get mmore attention and wax? That's and odd selection of a panel to do so.
 
GrnEyeDog said:
my 99 black 540 looks exactly like that on the hood and roof, trunk lid mysteriously doesn't have that defect.
Click to expand...

Setec Astronomy said:
You two must have the trunk force-field option.
Click to expand...

trekkeruss said:
I wonder if aerodynamics has anything to do with it.
Click to expand...

conman1395 said:
Why did your trunk lid get mmore attention and wax? That's and odd selection of a panel to do so.
Click to expand...

Setec Astronomy said:
Might also be the inclination, maybe water runs off better and flushes it more.
Click to expand...

One reason the trunk got more attention was I used it to try out a bunch of different detailing products, buffers, polishes, waxes, sealants, detailing sprays, etc. The trunk lid is small and easy to work with so was a good place to try various stuff, practice with buffers, etc. As a result it got more protection than either the roof or the hood. There may also be other environmental factors that I haven't considered.

Not sure if this is unique and linked to the type of clear coat the BMW used on the E39.

Regardless, the finish is now so smooth and mirror-like, I don't think anyone would notice the billions of *very* tiny pinholes. But would still like to hear from anyone that corrected the problem and understand how it was done and how much paint was removed.
 
My '99 Porsche 996 has this issue as well. It never showed until I had the car wet sanded and polished. It's on the hood, roof and a few other horizontal areas. I believe it pinholing from when the car was painted by Porsche. I've resigned myself to the fact that there's no fix besides repainting her.
 
I'm pretty sure this is what happened to my bros 73 maverick when I polished it..
His paintjob is prob only 6? years old
.but think it was cheap clearcoat..
Gonna polish it one more time and do opti gloss coating..then use either gtech liquid crystal or overcoat as booster
 
philh said:
Hello - My first post on the forum but passionate about detailing. Have learned a ton from Mike and the detailing experts on this forum.

So here's my issue.
Working on an old 2001 BMW 540 with Sapphire Black Metallic paint. The car was parked outdoors for 14 years and was used as a daily driver (180K miles). I've been busy rebuilding/restoring the car back to how it was when I picked it up in Munich many years ago.

While compounding/polishing the hood with my Rupes Bigfoot 15 (Starting first with the Blue micro-fiber cutting pad) I noticed thousands of tiny craters in the surface that appear to be environmental damage from years of rain/sun cycles etching the clear, or possibly the clear coat is simply degenerating. I noticed the same problem on the roof, but not on the trunk lid - possibly because the trunk received more attention (and wax) over the life of the vehicle.

So, thought I could remove these with something more aggressive than a Rupes and tried wet-sanded lightly with 2000 grit. I didn't goo too far and decided to stop since I didn't have a paint thickness meter and didn't want to go too far and end up past the point of no return. The surface is now extremely smooth, but the little pinholes are still visible - maybe even more visible because all the other imperfections are gone.

I took a high-res pic to better see the imperfections in the paint. In person it doesn't look like this bad to the naked eye, but wanted to illustrate what was going on.
(Light/dark transition magnifies issue).
Pitting_1.jpg



So, here are my questions:
1. Is this typical Clear Coat pitting from environmental damage?
2. Can it be removed by more aggressive wet sanding?
3. Any other suggestions other than repainting?

Thanks!
Click to expand...
Yes the pitting and craters are from the elements,with the age of the car just make it shine and accept it for what it is.sanding or high heat compound will only make the paint worse in shorter time the paint will be non repairable.so leave any material left on it and shine it up.
 
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