The Mystery Mark

F

fabz

New member
Hi everyone,



Every now and then when doing detailing jobs I come across this mark on cars paintwork. I call it "the mystery mark". It's almost always too deep to be sanded-buffed and my question is - Does anyone know what causes it?



Sorry if someone here talked about this before but I wouldn't know what to type to search for it.



Image can be seen here:



Link doesn't work, scroll down to see image



Thank you.
 
I don't know why as it works here and its not a private image... I'm not allowed to attach files so may try something else.
 
There it is:



IMXR0.jpg
 
Looks similar to when someone eggs a car, although that usually cracks the paint. This appears to be in the same shape, but doesn't look cracked.
 
I do question if it is egg created in every circumstance.

Can't really tell from the photo if it is that or another thing.

Here is why.

If this concern is observed more than once or twice a year, may be the result of a "plant fix" following the assembly of the vehicle, about 1 to 2 hours after it comes off the paint line.

If the affected area is aprox 2 to 3 inches in circumference, most likely due to a "spot buff" done following removal of a dust nib at the plant.

This was done reguarly for years.

The line guy has a special small sanding unit, most by hand, and they sand out the nib, then take an air buffer spinning very fast, with a 3M compound, then another buffer with a polish to remove the sanding marks.

Keep in mind that these employee's have aprox 52 seconds to 1 minute to do a spot.(figures from the Ford Oakville plant, Nissan Symerna, GM plant in Shreveport, etc)

They create excessive heat quite often when doing this repair, which themo stresses the paint film. The result shows up later, not talking about the little swirls, but much as you see in the photo. May take as long as two to three years, depending on wether the clear is a 1K or 2K and the paint suppliers material, color of the base coat (darker ones absorb more heat, thermo stressing again) and the enviorment in which the vehicle lives.

One method to learn about what it is, take a lighted magnifier and look closely at a spot "you are sure is an egg deposit", and learn the "pattern" of the defect.

Then start looking at other similar defects, you will notice the difference between the two.

Just something to consider.

Grumpy
 
I think I come accross this too often to be eggs but the fact that it's always around the same size - about 1 and a half inch and from what I remember always on side panels, eggs are a possibility. I think an approximate 1 in every 40 - 50 cars I work on will have this mark! Easy 2%.



At the same time I've seen the damage eggs can do to paintwork it it's left behind, it can eat the paintwork to bare metal like the most evil bird poo and around these marks I normally do not see clearcoat damage... mysterious...
 
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