How should I handle dirt buildup at the seams of the clear bra?
It is almost inevitable that you will have some seams with your clear bra/paint protection film/PPF. It is not cost-effective for most clients to choose to pay a premium to have no seams at all compared to how much extra protection it provides. Remember that it is paint protection film, not paint perfection film.
Over time, these edges may begin to accumulate some dirt, making them more visible. This is especially true for lighter-colored vehicles, where the darker dirt line is more obvious. The best way to handle these buildups is a combination of having us also install a ceramic coating on your entire vehicle at the time you have it covered in clear bra, and using a soft-bristled toothbrush when you foam your car to lightly clean the edge.