Q: How do they apply those huge...

Q: How do they apply those huge ads that cover buses?

A: The design is created on a computer terminal and is tailored to the dimensions of the bus that will carry it. It is then printed in sections on 34-square-inch sheets of thin vinyl that have a self-adhesive material on the back, made by SuperGraphics Inc. of Sunnyvale. A second layer of vinyl is then applied to protect the design from dirt. Sheets that go over the windows are perforated so that passengers can see out.

At the installation site, workers peel the protective paper from the adhesive and apply the squares like wallpaper, starting with the windows. The vinyl is so thin that windows and emergency doors can be opened easily. The vinyl can be peeled off later, but it is often heated with a torch to make removal easier.