What is this stuff and how do I remove it? (paint)

Roof rack is removed, and since I'm waiting for some parts I want to clean things up. The checking/cracking in the paint is probably due to the shoe goo that was on there, not much I can do about that. It's under the rack so I don't care too much about it. However the white stuff that's accumulated at the edge of the roof rack is tough crud! I hit it with some compound and it just laughed at me. Acetone won't do anything to it either.

Any speculation as to what this stuff is and how/if it can be cleaned up without causing collateral damage?

try clr

Aha, yes. I will give that a try!

Well, Nick, that was a great suggestion but so far it didn't do anything. I probably should have mentioned that the stuff is a brownish color, the white color came after attempting to compound it out.

I tried a bunch of different things, and finally gave in and bought a clay bar. The clay hangs up on the stuff, but doesn't remove it. I think I'd need to get a buffer to get this stuff out.

Unless anyone has any other suggestions, I feel that I gave it a go and I'll just wax over it and call it done.

On the plus side, I've never used clay on a car before, and I'm a believer in this stuff now. I'm going to clay the whole car (well, the parts that are painted, anyway)

I was thinking clr as well.  Did you let it sit for a while and hit it with some elbow grease?
I've had some calcium build-up around faucets and other things that take a good long soaking to really even start to get the build-up to release.  Sometimes repeated soakings are needed for a heavy deposit.

Wood plane? Razor blades? Steel wool?

Could it be the clear-coat that is cracking and breaking down? Clear polyurethane is really tough stuff. After a paint job, when you sand and buff the clear-coat, if you don't quickly get all the clear powder off that ends up in crevices, you will never get it off. I have a couple little spots that I missed in the corner of a door post, and it looks very similar to what you have, only smaller.

I let the CLR sit, but you can't let it sit too long or it evaporates.

It could definitely be that the clear coat is damaged and that what I'm seeing isn't on the paint but actually in the paint.

Going over it several times with the clay bar at least smoothed it out a bit. It's rough though, the clay sticks to it, and a silicone drying blade also gets hung up by it.

I just ended up waxing over it and put the roof rack back on.

if the clr did nothing,.

my next best interenet photo diagnosis guess, would be,
sometime or another somebody re-clear coated the roof withoit removing the roof rack

now the roof rack is back on,.. when u drive at 30mph on a wet day past someone standing on the curb
i'll bet they won't even notice it now

Yeah, it would be pretty hard to spot.

If I were carrying around a small black hole it might be visible from passers-by, but I'd need some pretty stout suspension upgrades before I could do that.

Re-clearing is an interesting thought. The marks are at the edge of the rack plastic, and they go both under the plastic and into the exposed parts of the paint. Maybe something leached out of the plastic and damaged the paint, or possibly it stems from whatever that glue was that was put on in an attempt to water seal the rack.

It's curious to me, but unless you're standing on a ladder and looking down at the roof, nobody will care. I just wanted to clean it off and prevent further damage while it would have been easy to do so.

lamune wrote:

If I were carrying around a small black hole it might be visible from passers-by,

er,....pardon?

You need a lot of mass to bend light enough to make those seams and marks visible.

Or you'd need to be going pretty close to the speed of light. I'd need a really, really big block to do that!

Having the rack off and being able to get in there and clean and wax the paint did wonders though, out in the rain the water is beading and rolling off nicely. It should be good for many years to come (I hope)

Anyway, back on topic. I was able to determine that the clear coat is damaged.

Nothing a repaint won't solve.