Animation cels (short for celluloid), are transparent sheets on which objects are drawn or painted for traditional, hand-drawn animation. They make production far easier by reducing the amount of times studios have to redraw an image. The outline of the image is drawn on the front of the cel while colors are painted on the back to eliminate brushstrokes.
"Cel paintings are the final step in the intensely laborious process of animation. The artistic process begins with the storyboard, which illustrates the action of the script. Next, animators create pencil drawings that give life and movement to the characters. After the drawings are transferred onto acetate, the cels are meticulously hand-painted. Once the production of each episode is complete, Disney cleans and touches-up many television production cels. In some cases, this process is so meticulous that Disney hand-inks over existing lines."
Disney usually places "certificates of authenticity" on the back of their cels to vouch for their authenticity. They are traditionally enclosed in transparent envelopes and sealed with gold Mickey Mouse stickers and are placed to "certify that all in information and statements contained herein are true and correct".
Nowadays, animation cels are considered collector's items if released to the public after production, because every cel is one-of-a-kind and unique and can fetch a hefty price. Disney especially can make a lot of money out of selling them. Cels that were not used in production that are sometimes considered to be "limited artwork" are usually less expensive than properly hand-painted cels.
Below follow a series of cels released for Buzz Lightyear of Star Command, in order of the episodes they appeared in. It was originally thought that there were only seven cels in existence (five from "Wirewolf" and two from "The Adventure Begins") but since then several more cels have been appearing for sale on auction-based websites.
The Adventure Begins
A Zoo Out There
This is to certify that the accompanying piece of art is an Original Production Cel from the episode "A Zoo Out There" of Walt Disney Television Animation's cartoon series "Buzz Lightyear of Star Command".
Whereas the film "Toy Story" introduced the Buzz Lightyear character as an action figure come to life (courtesy of computer-generated images), "Buzz Lightyear of Star Command" presents the traditionally-animated television series upon which the toy was based. "Buzz Lightyear of Star Command" focuses on the adventures of the title character as he patrols the galaxy with his team of Space Rangers, battling evildoers "to infinity... and beyond." "Buzz Lightyear of Star Command" premiered on ABC in Oct. 2000.