Acetate

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Definition

Acetate is a clear plastic sheet (cellulose acetate) once common in film and animation. In stop-motion, it shows up as cell material, overlays, or practical effects that require transparency.

Context

On a puppet stage, acetate can be used for in-camera tricks: false reflections, smoke layers, or transparent props. Historically, it was the base material for 2D cel animation. In VFX, painted acetate sheets were sometimes used for mattes or optical composites.

Related: Cel Animation, Matte, Overlay, Transparency

Examples

• A sheet of acetate angled in front of the camera to fake window reflections in a miniature set.
• Painted clouds or smoke on acetate, placed between camera and puppets, to add depth.
• Traditional cel animation, where characters were inked on acetate cels and stacked over backgrounds.

Notes

• True cellulose acetate has mostly been replaced by safer plastics, though the word “cel” is still used.
• Heat from stage lights can warp acetate, bending reflections or painted overlays.
• Acetate film stock degrades over time, producing “vinegar syndrome,” a strong smell and visible shrinkage.

Media

• Diagram: a stack of acetate cels layered over a painted background.
• Clip: cel overlays combined with stop-motion footage.