Preping the stiffners and skin for riveting and sealing. This process takes a lot of time and effort to clean all the surfaces of grease and oil from the manufactureing process. Using scotch brite green pades and Methelethal Ketone to clean. I used the black and decker power screw driver with the deburring tool and a small patch of scotch brite pad cleaning the rivet holes on the skin is very easy.
