Cel - Short for "celluloid,"
the term refers to the
clear sheets of celluloid on which animated
characters were traced from the animators'
cleaned up pencil drawings, painted, and then
photographed on top of a background. Cels
were made of nitrate cellulose until 1940, then
cellulose acetate in later years. With 24 frames
per second of film, there could be as many as 24
cels per second, but normally, cels were held for
two frames. Thus a film like "Snow White" might
have as many as 60,000 cels. The use of cels
ceased in the late 1980s as computers were
adapted to accomplish the same task.