Paint defect? What is it, and how do I get rid of it?

[pbsadtler]

Hello all,

I was washing my car today and noticed these little pin-head sized paint bumps on the rear trunk lid. They look like possible overspray marks or dirt that got caught in the paint. Can anyone help me identify them? What would be the best way to remove them? Or should I just leave it alone? Many many thanks in advance.

I circled the area on the attached photo. The dots are about twice as big in the photo as they are on the car. It was hard to get a good picture with the glare from the sun.

48967

[irvsmith]

Given that they are bumps it is most likely above surface bonded contaminants as Mike Phillips describes them. I would start with a clay and clay lubricant on a small section of them. See if they come up. If not you might need to step it up to an IPA solution.

[pbsadtler]

Alright, that sounds like a good start. I was planning on doing a clay/wax next weekend, so hopefully that does the trick. Any chance it's something more serious, like paint blistering/beginning to fail?

[precisionmobile85]

From the picture imo it looks like its under the paint and not a contaminent on top of the clear. Hard to tell in the pic

[Setec Astronomy]

How old is the car? Has it ever had any body work?

[pbsadtler]

2007 Porsche Cayman. I bought it last year from a reputable place near me. they said they believed it has not had body work, and the pre-purchase inspection was clean as well (i specifically asked about repainting). but the car lives outside and is exposed to the elements. if it's just a surface contaminant or a bit of dirt under the paint, i can probably live with it (assuming i can't fix it). my biggest concern is that whatever is trapped under the paint will expand and turn into an ugly bubble. i can't imagine that having a Porsche painted comes cheap...

[Setec Astronomy]

Well, IMO it's definitely not on top of the paint. It does look like it could be the start of rust bubbles, but honestly they look too "smooth" for that.

[pbsadtler]

I don't have any experience with rust bubbles... would they be "hard" to the touch like sandpaper, or would they be kinda soft like a blister on your finger?

[Setec Astronomy]

It kind of depends where they are in the corrosion cycle. At some point you will be able to pop a rust bubble, but at the beginning they may be hard--I try not to push on them unless I'm ready to fix them.

[pbsadtler]

Alright, thanks very much for your help. I've actually noticed that these little dots are in several different places on the trunk lid. There's one cluster of about 20 of them, then there's another small area that has 2 or 3, then there's another different area that has 2 or 3. They're not centralized and there's no clear rhyme or reason why they are where they are. I'm now thinking that some panel (like the rear bumper or spoiler) was re-painted and these little dots are overspray from a bad tape job. Wouldn't it be unlikely for rust to appear simultaneously in that many different locations? I guess anything is possible.

[Setec Astronomy]

They don't really look like overspray. Top of the trunk would be an unlikely rust spot. Edges or bottom would be more likely, I wouldn't worry about it too much, they do look like they could just be something under the paint, they are too rounded to be something "in" the paint that got on there after spraying, they look like something that were sprayed over.

Since we're talking about rust, is that lid even steel? I don't know much about Porsches, but apparently the newer Caymans have an aluminum trunk lid, from a quick Google.

[pbsadtler]

The front trunk lid is aluminum, but the rear trunk/doors/etc. are steel. I've run a magnet over it. Yea, I would think rust would be more likely on the edge of a panel and none of these little bubbles are on an edge. Very odd. This car has taught me that it doesn't matter how much homework you do on a used vehicle, you're going to inherit some issues.

[Setec Astronomy]

I'd stop worrying about this and enjoy the car. If they are rust bubbles (which I don't think they are) there is nothing you can do about them (to arrest their progress), and if they aren't...so you have some bumps in the paint that no one will notice except you.