Cel animation

Cel animation also known as Hand-drawn animation was the conventional method of producing animation for film and later television throughout the entire 20th century. For professional productions such as Arthur, it involves tracing over finalized sketches with ink on a clear celluloid sheet and then coloring the other side of the sheet with the appropriate paint colors to make up a frame of the animation once the cel is captured with photography over the appropriate background. Once cel animation became popular among production companies, it became a common practice to outsource finalized animation using cels (and sometimes the cels themselves) from specialized overseas companies for cost effectiveness. AKOM, for example, is an overseas animation company that provided animation services for Arthur. Cel animation was utilized for the show from the start of the show until the end of season three. From the fourth season until the 15th, Arthur would be animated using the cheaper, digital ink and paint method.

Production

Every animation cel is based on a pre-production sketch (not to be confused with storyboards) produced by Cookie Jar Entertainment (then called CINAR). The sketches were shipped to AKOM to be traced over on a celluloid sheet with ink. Cels were then painted on the other side using the appropriate paint colors. Specific reference sheets made to direct animators on what colors a character or object should be specifies to the animators the ideal look of what the said character or object should look like in a specific scene (i.e,, dark and bright settings, variations in clothing, etc). Cels were then allowed time to dry and are then included when every frame of an episode is captured using photography. Cels were then meant to be laid over the appropriate watercolor backgrounds also made by AKOM.

To save time, moving mouths were commonly given their own cels. This also allowed reduction to the overseas animator's workload as a character's body did not need to be redrawn and painted just to complement another frame of their mouth. Occasionally, head movements were allowed possibility through separate cels.

To make the animation more lively, mask budget restraints and to achieve zoom ins, outs and pans, camera movement was implemented during photographic captures of the cels over backgrounds. Sometimes, a singular painting was made to complement camera movements. This technique was most commonly used in the show's earliest produced episodes of the first season. In other instances, such as walking or general movement of an object shots, the background was moved with every captured frame of cels in a sequence while the camera stayed in a position.

Creating Arthur cels was an unique process because its art style. Pencil strokes for the specific outline style of Arthur in general, which include gaps in outlines, were preserved when sketches are traced over on a cel and, to an extent, when backgrounds were created. Consistency in where gaps in outlines are present in characters and objects drawn on cels were kept to a minimum which makes a unique effect when the characters and objects move in the final animation. The finalized animation took months to ship back to CINAR from AKOM in Korea.