What is Production Cel?
Cel is the term for celluloid picture. It is a transparent material used to make frames of animation in the production of animation films. Each cel is one frame. To create the illusion of movement, each drawing differs slightly from the one before it, then the completed cels are photographed one-by-one against a painted background by a rostrum camera onto motion picture film to produce the final animation.
When creating the cel, the frame is initially drafted out, then a cleaned up version of the sketch is made. The accompanying sketch includes the outline of the image and instructions for the next artist for shading, colouring and framing of the shot. This pencil sketch is then placed underneath the celluloid and traced with ink.
Once the sketch has been traced, the image is then turned over and coloured in using acrylic paints on the back side. The information about a cel’s location in a sequence is contained in the top right hand corner of a cel, consisting of a letter and a number. The letter represents the layer of the cel, while the number is the position of the cel in the sequence. The first cel has the number "1". If the cel is the last in a sequence, "end" will be written next to it. The first and last cels in a sequence will generally be ‘key cels’.
The majority of these production techniques have since been suspended by digital animation. The initial concept sketches are still done by hand, but rather than being painted on cels, they are now scanned and the rest of the production completed on computers. This result is this process is much faster and cheaper to produce, but it makes the hand-produced items rare collectors’ items. The general transition point to digital took place after 2001, so more modern shows such as Naruto and One Piece will generally only have their sketches available .