What is a cel?
A cel (short for celluloid) is a transparent sheet of acetate that carries one drawing in a shot. The character's outline is traced onto the front of the sheet and the colors are hand-painted on the reverse, so the paint sits behind clean, unbroken lines. Each cel is photographed over a painted background to expose a single frame of film.
How cels were used
For most of the twentieth century, hand-drawn animation was shot cel by cel. A frame might stack several cels — an A layer for the body, a B layer for a moving mouth, a C layer for a foreground prop — over a single background. Only the layers that move need to be redrawn, which is why a held pose can share one cel across many frames.
Inking and painting
Early cels were hand-inked: the line was traced onto the acetate with pen or brush. From the 1970s most studios adopted xerography, photocopying the pencil line directly onto the cel. Paint was applied by hand in flat, opaque areas of animation-specific cel paint.
What to look for
- Painted on the back, traced on the front.
- A cel number written or stamped along an edge, identifying the cut and layer.
- Peg holes for registration.
- Original production cels are one-of-a-kind; distinguish them from sericels and reproductions, which were made for sale rather than filming.