A cel, short for celluloid, is a transparent sheet on which objects are drawn or painted for traditional, hand-drawn animation. Actual celluloid (consisting of cellulose nitrate and camphor) was used during the first half of the 20th century. Since it was flammable and dimensionally unstable, celluloid was largely replaced by cellulose acetate. With the advent of computer-assisted animation production (also known as digital ink and paint), the use of cels has been all but obsolete in major productions. The Walt Disney Animation Studios stopped using cels in 1990, when Computer Animation Production System (CAPS) replaced this element in their animation process.[1] In the next decade and a half, other animation studios phased cels out as well in favor of digital ink and paint.
Disney's next animation smash was The Little Mermaid - the last Disney feature to utilize hand-painted acetate cels... Beauty and the Beast, Disney's next hit animation feature, was the first to use, instead of hand-painted cels, Disney's "CAPS" computer-generated characters.