If you just mask the stripes, then shoot color, then clear, you'll wind up with a ridge in the paint at the edge of the stripe. I did mine by masking, then color, then unmasked it, then cleared the entire hood, roof and trunk area. If you shoot three good coats of clear, you can buff out the ridge. There's really no need to rush getting clear on the base, since you have 24 hrs with most paint systems. I've also learned the hard way to make very, very sure the car is clean after you unmask the stripes, before you shoot the clear. Unmasking breaks off all kinds of little bits of base and they seem to hide in the masking paper where you mask off the windows. I would re-mask the whole car before clear if I were you rather than risk blowing out debris into your fresh clear.
Yep, I know about the ridge, that is why I was asking.
I was always tought to rough up the surface before shooting. So you shoot clear on the car without roughing up the clear that is all ready on the body? It bonds well like that?
No, you absolutley need to scuff the existing clear first. There are two types of adhesion in paint: chemical and mechanical. Chemical bonding takes place when you apply clear over fresh base. You generally have a time limit (no sooner than 15 minutes, no longer than 24 hrs) in which to apply clear over base or clear. If it's been longer than 24 hrs, you must create a "mechanical" bond by creating small scratches for the paint to adhere to. I've used grey 3M scuff pads in tight places (door jambs) and 500 grit wet paper to scuff paint, both with great results and niether method will show after the final clear. However, you cannot sand bare base with no clear over it, but you can usually use a scuff pad to get a bit of dirt out of non-metallic base before clear with no problems. Sanding or scuffing metallic base for whatever reason will ruin the metallic. Also, when shooting base over clear (like your stripes) be very, very careful to use LIGHT coats. If you try to shoot heavy coats of base over clear to avoid orange peel, you'll likely get huge wrinkles that go clear to the primer of the original paint. The reducer in the base can and will eat into the original paint and cause no end of headaches. Just use be patient and shoot more light coats rather than trying to cover it in a couple heavy coats and you'll be fine.