Clay animation or claymation, sometimes plasticine animation, is one of many forms of stop motion animation. Each animated piece, either character or background, is "deformable"—made of a malleable substance, usually plasticine clay.
Traditional animation, from cel animation to stop motion, is produced by recording each frame, or still picture, on film or digital media and then playing the recorded frames back in rapid succession before the viewer. These and other moving images, from zoetrope to films to video games, create the illusion of motion by playing back at over ten to twelve frames per second. The techniques involved in creating computer-generated imagery are conversely generally removed from a frame-by-frame process.
Each object or character is sculpted from clay or other such similarly pliable material as plasticine, usually around a wire skeleton called an armature, and then arranged on the set, where it is photographed once before being slightly moved by hand to prepare it for the next shot, and so on until the animator has achieved the desired amount of film. Upon playback, the mind of the viewer perceives the series of slightly changing, rapidly succeeding images as motion.
A consistent shooting environment is needed to maintain the illusion of continuity: objects must be consistently placed and lit, and work must proceed in a calm environment.
Producing a stop-motion animation using clay is extremely laborious. Normal film runs at 24 frames per second (frame/s). With the standard practice of "doubles" or "twos" (double-framing, exposing two frames for each shot) 12 changes are usually made for one second of film movement.  Shooting a 30-minute movie would therefore require making approximately 21,600 stops to change the figures for the frames; a full-length (90-minute) movie, 64,800—and possibly many more if some parts were shot with "singles" or "ones" (one frame exposed for each shot).
The object must not be altered by accident, slight smudges, dirt, hair, or dust. Feature-length productions have generally switched from clay to rubber silicone and resin cast components: Will Vinton has dubbed one foam-rubber process "Foamation". Nevertheless, clay remains a viable animation material where a particular aesthetic is desired.
Clay animation can take several forms:
"Freeform" clay animation is an informal term referring to the process in which the shape of the clay changes radically as the animation progresses, such as in the work of Eli Noyes and Ivan Stang's animated films. Clay can also take the form of "character" clay animation, where the clay maintains a recognizable character throughout a shot, as in Art Clokey's and Will Vinton's films.
One variation of clay animation is strata-cut animation, in which a long bread-like loaf of clay, internally packed tight and loaded with varying imagery, is sliced into thin sheets, with the camera taking a frame of the end of the loaf for each cut, eventually revealing the movement of the internal images within. Pioneered in both clay and blocks of wax by German animator Oskar Fischinger during the 1920s and 1930s, the technique was revived and highly refined in the mid-1990s by David Daniels, an associate of Will Vinton, in his 16-minute short film "Buzz Box".
Another clay-animation technique, one that blurs the distinction between stop motion and traditional flat animation, is called clay painting (also a variation of the direct manipulation animation process), wherein clay is placed on a flat surface and moved like wet oil paints (as on a traditional artist's canvas) to produce any style of images, but with a clay look to them.
A sub variation clay animation can be informally called "clay melting". Any kind of heat source can be applied on or near (or below) clay to cause it to melt while an animation camera on a time-lapse setting slowly films the process. For example, consider Vinton's early short clay-animated film Closed Mondays (co produced by animator Bob Gardiner) at the end of the computer sequence. A similar technique was used in the climax scene of Raiders of the Lost Ark to "melt" the faces of the antagonists.
The term "hot set" is used amongst animators during production. It refers to a set where an animator is filming. The clay characters are set in a perfect position where they can continue shooting where they left off. If an animator calls his set a "hot set," then no one is allowed to touch the set or else the shoot would be ruined. Certain scenes must be shot rather quickly. If a scene is left unfinished and the weather is perhaps humid, then the set and characters have an obvious difference. The clay puppets may be deformed from the humidity or the air pressure could have caused the set to shift slightly. These small differences can create an obvious flaw to the scene. To avoid these disasters, scenes normally have to be shot in one day or less.
Clay-animated films were produced in the United States as early as 1908, when Edison Manufacturing released a trick film entitled The Sculptor's Welsh Rarebit Dream (possibly referencing the comic strip Dreams of a Rarebit Fiend). In 1916, clay animation became something of a fad, as an East Coast artist named Helena Smith Dayton and a West Coast animator named Willie Hopkins produced clay-animated films on a wide range of subjects. Hopkins in particular was quite prolific, producing over fifty clay-animated segments for the weekly Universal Screen Magazine. By the 1920s, cartoon animation using either cels or the slash system was firmly established as the dominant mode of animation production. Increasingly, three-dimensional forms such as clay were driven into relative obscurity as the cel method became the preferred method for the studio cartoon.
Nevertheless, in 1921, clay animation appeared in a film called "Modeling", an Out of the Inkwell film from the newly formed Fleischer Brothers studio. "Modeling" is one of the few known shorts using clay that was released during the 1920s. "Modeling" included animated clay in eight shots, a novel integration of the technique into an existing cartoon series and one of the rare uses of clay animation in a theatrical short from the 1920s.
Pioneering the clay-painting technique was one-time Vinton animator Joan Gratz, first in her Oscar-nominated film The Creation (1980), and then in her Oscar-winning Mona Lisa Descending a Staircase, filmed in 1992. 
In 1972, at Marc Chinoy's Cineplast Films Studio in Munich, Germany, André Roche created a set of clay-animated German-language-instruction films (for non-German-speaking children) called Kli-Kla-Klawitter for the Second German TV-Channel; and another one for a traffic education series, Herr Daniel paßt auf ("Mr. Daniel Pays Attention").
A variation of clay animation was developed by another Vinton animator, Craig Bartlett, for his series of Arnold short films (also made in the late-1980s/early-1990s), in which he not only used clay painting but sometimes built up clay images that rose off the plane of the flat support platform toward the camera lens to give a more 3-D stop-motion look to his films.
Some of the best-known clay-animated works include the Gumby series of television show segments (created by Art Clokey)  , The California Raisins advertising campaign by Will Vinton Productions studio and The WB's The PJs, produced by and featuring the voice of Eddie Murphy. Clay animation has also been used in Academy Award-winning short films such as Closed Mondays (Will Vinton and Bob Gardiner, 1974) , The Sand Castle (1977), Creature Comforts (Aardman Animations, 1989), and all four Wallace and Gromit short films, created by Nick Park of Aardman Animations. Aardman also created The Presentators, a series of one-minute clay-animation/CGI short films aired on Nickelodeon UK. Some clay animations appear online, on such sites as Newgrounds. In addition, many of the Rankin/Bass holiday specials were clay-animated. 
Several computer games have also been produced using clay animation, including The Neverhood, Clay Fighter, Platypus, Clay Moon (iPhone app), and Primal Rage. Television commercials have also utilized the clay animation, such as the Chevron Cars ads, produced by Aardman Studios. Besides commercials, clay animation has also been popularized in recent years by children's shows such as Pingu, Shaun the Sheep and Mio Mao as well as adult-oriented shows on Cartoon Network's Adult Swim lineup, including Robot Chicken (which uses clay animation and action figures as stop-motion puppets in conjunction) and Moral Orel. Many independent young filmmakers have used clay animation features for internet viewing.
Flushed Away is a CGI replication of clay animation.  Probably the most spectacular use of model animation for a computer game was for the Virgin Interactive Entertainment Mythos game Magic and Mayhem (1998), for which stop-motion animator and special-effects expert Alan Friswell constructed over 25 monsters and mythological characters utilising both modelling clay and latex rubber, over wire and ball-and-socket skeletons. Rather than building the models in the cartoon-like style of Wallace and Gromit, Friswell constructed the figures after the designs of Willis O'Brien and Ray Harryhausen to make them more compatible with the game's often violent playing tactics.
Notable clay animators
- "Case study: Chicken in Clay" (1997)
- Animation Techniques: Stop-Motion-NFB Blog
- Gumbo (2003)
- Oddball Films: Stop-Motion Explosion III - Thur. Aug 15 - 8PM
- "Clay Animation – Clay Animation History". Wordpress. Retrieved 26 February 2013.
- Frierson, Michael (1993). Clay comes out of the inkwell (in Animation Journal - Fall 1993).
- Sarson, Katrina (April 27, 2017). "Animator Joan Gratz Embraces Technology To Create Her Newest Films". Oregon Public Broadcasting. Retrieved January 30, 2018.
- History of Clay Animation-Peeble Studios
- Oddball Films: Will Vinton's Claymation Marvels - Thur. June 12 - 8PM
- A History of Clay Animation-ABC News
- "First look at Aardman's rat movie". BBC News Online. BBC. 16 February 2006.
- STOP-MOTION MARVELS: “George Washington Modeled in Clay (1927) and “Red Riding Hood” (1926)-Cartoon Research
- Taylor, Richard. The Encyclopedia of Animation Techniques. Running Press, Philadelphia, 1996. ISBN 1-56138-531-X
- Lord, Peter and Brian Sibley. Creating 3-D Animation. Harry N. Abrams, Inc., New York, 1998. ISBN 0-8109-1996-6
- Frierson,Michael. "Clay Animation: American Highlights 1908 to the Present." Twayne Publishers: New York, 1994. ISBN 0805793275