Horizontal Black Streaks (aka "Zebra Stripes")

[TimL]

Hey Folks,


 


I drive a white 2007 F150 with an Undercover tonneau cover.


For the past couple of years, any time it rains I get black horizontal streaks running down the sides of the bed.  I am also getting similar streaks beneath the black plastic side mirrors.


I can wash the entire vehicle, including the tonneau cover, and if it rains the next day, the streaks are back.


I've been driving the truck since it was new, and I've noticed this issue becoming worse over the past couple years.


I wash the truck with Duragloss car wash, and then apply Duragloss Aquawax.


 


Am I overlooking something?


 


Should I be washing the black plastic parts with a special cleaner?


 


Should I be applying some sort of sealer to the plastic tonneau cover to prevent contaminates from adhering?


 


Thank you in advance for the advice.


 


Tim

 

[Accumulator]

TimL- Just an educated guess, but it sounds to me like one of two things: 


 


1) the stain-causing stuff is coming off the black plastic bits.  Some of that could be from any dressing that's been used on such materials, or from oxidation of those bits if they haven't been adequately protected.  OR,


 


2) if not coming off the trim, it could be dirt that builds up in/around/behind those areas and then gets flushed out onto the paint by a combo of rain and airflow.


 


So I'd want to deal with both issues.  First, I'd plan on getting plastic bits all cleaned up and sealed so they are eliminated as a source of the problem, and are also all properly detailed for both appearance and protection.  If the problem continues after that, it's most likely from the previously mentioned dirt build up and you'll just have to do a more thorough job of cleaning the area in question (easier said than done when it's behind something, huh?!?).


 


If it were mine, I'd use my standard regimen for exterior trim- clean with Griot's Rubber Prep, seal it with Ultima's Tire and Trim Guard Plus, maintain with ValuGard's FastFinish (you could use your AquaWax instead).


 


I'd really focus on getting those surfaces *VERY* clean, including the nooks and crannies like around the edges of the pieces (think about dirt getting in the gaps between the pieces and the surrounding paint).  I"d want to know that I'd eliminated as much of that "seemingly obvious source of the problem" as possible.   Also, you might consider switching to a more dirt-shedding LSP that will make cleaning the black streaks off go easier.  I have some areas on my Tahoe that leave vertical dirt streaks if I go too long between washes, but those stains wash right off the FK1000P without leaving any artifacts behind.