We print mainly billboards day in and day out. We print self adhesive but do not install so I need some help. Just had a billboard installer stop by with a weird question. He asked if I could print on the back of a billboard. My first question was why. He explained that when a billboard posting expires and there is not one going up right behind it they flip the board around and use the blank side of the vinyl. He then wants the back side to say available with his phone number. I told him we could print a self adhesive imprint and stick it to the billboard. He told me this has been tried and after the board has been up for a while no matter how much he cleans the surface the self adhesive will not stick. He says that is because of the emissions from the cars build up a film making it impossible to get anything to stick. I then told him there might be an adhesion promoter he could apply but not sure and I would do some research. Is there such a thing? When installing car wraps, do you have problems with adhesion around the exhaust? Printing on the back is defiantly out.