Peter80

Just about to touch up a few chips with Dr Colourchip on Jet black metallic. A few quite big chips / minor road rash on the lower side skirts/sills towards rear in front of rear wheel arches, just below those film protection panels, where the bit nearest the ground and below doorline is thicker mottled paint. Noticed that where the black paint is chipped out, it shows white. I bought the car last May, 17 months old with immaculate bodywork. Is the white undercoat normal on this part or is it likely there's been some repair, possibly even filler, and respray work carried out. Just wondered if anyone out there has experience of this. Thanks.

justabout

arter

Yep, normal.
Buy a white car next time to reduce touchup.

Al.Fresco

White under black here as well.

StormRune

On the lower surface there is a plasticized undercoating on the paint to make it more flexible and less chip prone and less like to penetrate to metal and cause rust. You can see the line where it stops like you observed (the "mottled" area). That undercoating seems to be white. I'd assume we'd have more chipping without it, so I guess it is a compromise.

When I had my PPF applied, we decided to do an experiment and added a second short layer of PPF right over that "mottled" paint line to see if that will help more than just a single thin later. The second layer covers the mottled area, going from the car bottom and ends right at the top edge of the that area. It is virtually invisible due to those lines matching up. My installer says he can remove that outer thin layer if it gets beat up without pulling off the main PPF. So far so good on it with 4k miles that way,