Airbus uses a process in manufacturing called 'Bonded Primer'. This is a chemical treatment that is applied to the sheet stock aluminum before it is made into the skin panels and gives it that 'green look'. This is because European metal works company's do not use 'Alclad', which is a corrosion inhibitor. 'Bonded Primer' must not be removed or disturbed at anytime and is why you never see, with the exception of American's A300, a bare metal Airbus. The Bonded Primer is more clearly shown in this pictureView Large View Medium
Photo © Pierre-Clément Got
Boeing uses 'Alclad' sheet stock, which can remain bare metal if the airline so chooses. There is a thin protective treatment applied to Alclad to prevent minor scratching and light corrosion before the painting or polishing process. This treatment is what gives the Boeing's that funky blue color when being built. It is normally removed with a special wash.
[Edited 2005-09-09 04:07:00]
"It's not the size of the dog in the fight, but the size of the fight in the dog"