http://www.fxguide.com/article557.html
fxg: Can you talk about the elements shoot for the ink?
Tim Regan: We used many methods to control how the inks mixed into the white of the paper. A light box was built which allowed us to incrementally change the following variables: the angle of the paper, the source of light, the wetness of the paper, the amount of ink poured on the paper, the weight and tooth of the paper. While the smallest change in any of those variables led to extremely different results, the light box's design allowed us to really fine tune the speed and spread of the ink into the paper.
Aaron Maurer: We also used a grease pencil on the paper to control where ink would or wouldn't go. This came in handy when we had certain shapes from the live action footage we knew were going to be filled in with color in the the animation. We could draw out the general shape of a car or the Shell logo and have it fill in with ink naturally.
fxg: Can you talk about the elements shoot for the ink?
Tim Regan: We used many methods to control how the inks mixed into the white of the paper. A light box was built which allowed us to incrementally change the following variables: the angle of the paper, the source of light, the wetness of the paper, the amount of ink poured on the paper, the weight and tooth of the paper. While the smallest change in any of those variables led to extremely different results, the light box's design allowed us to really fine tune the speed and spread of the ink into the paper.
Aaron Maurer: We also used a grease pencil on the paper to control where ink would or wouldn't go. This came in handy when we had certain shapes from the live action footage we knew were going to be filled in with color in the the animation. We could draw out the general shape of a car or the Shell logo and have it fill in with ink naturally.