Squash and Stretch: Bringing Life to Animation

Squash and stretch is the cornerstone of dynamic animation, a tool animators have relied on to breathe life into characters and objects since the golden age of Disney. Whether it's the exaggerated deformation of a bouncing ball or the expressive facial movements of a character, this principle of animation is essential for creating believable motion and depth. In this article, we'll break down what squash and stretch is, how it fits within the twelve basic principles of animation, and how you can apply it to elevate your animations to the next level.

Squash and Stretch - What Is It?

At its core, squash and stretch is a technique used to exaggerate the shape and form of an object in motion. The goal is to give the object a sense of weight and flexibility by deforming its shape without compromising its volume. A classic example is the bouncing ball animation. When the ball hits the ground, it "squashes" outwards, compressing along the vertical axis. As it ascends, it stretches along the same axis, giving the ball an illusion of momentum and elasticity.

This principle doesn't only apply to inanimate objects but is pivotal in character animation as well. In fact, it’s often one of the first concepts taught to new animators because it immediately brings static drawings to life.
In this video by Frame by Frame Animation, see if you can spot where squash and stretch occurs in the first 5 seconds (keep on watching to find out if you were right!):

Principles of Animation: Understanding Squash and Stretch

Squash and stretch is the first of the twelve basic principles of animation, conceptualized by Frank Thomas and Ollie Johnston in their book, Disney Animation: The Illusion of Life. These principles form the backbone of classical animation and are just as relevant today as they were in the 1930s.

The beauty of squash and stretch is that it creates the illusion of life while adhering to real-world physical concepts like elasticity (physics) and volume. Despite the exaggerated deformation, an object must retain its original mass—otherwise, it can lose believability.

For example, a bowling ball will squash far less than a rubber ball because of its density and rigidity. However, applying even a small degree of squash and stretch to the animation of a heavy object still helps to emphasize its motion and weight.

The Application of Squash and Stretch in Animation

Squash and stretch is a universal tool that can be applied to all forms of animation. From the hand-drawn cartoons of the past to the cutting-edge 3D animations of today, it plays a critical role in crafting visually engaging and believable characters and objects.

Examples in Traditional Animation

Traditional animation is where squash and stretch truly made its mark. Consider the early Disney cartoons like "Steamboat Willie" or the animations from Warner Bros. Cartoons where characters like Bugs Bunny or Daffy Duck are in constant motion. These characters stretch when they leap and squash when they hit the ground, even if they’re not realistic representations of how actual bodies behave.

Another iconic example is the flour sack animation exercise, a common practice among animators to convey a range of movements and emotions using a simple, amorphous shape. Squash and stretch helps give the sack a life of its own, whether it's dancing, collapsing, or reacting to external forces.

Here’s an example of the flour sack exercise by Nishant Trivedi on Youtube:

Examples in Modern Animation

In modern 2D animation, squash and stretch has become more refined, often used to convey subtler emotional nuances. Recent examples include films from Pixar and DreamWorks, where squash and stretch are applied to create more organic and detailed character movements. In these cases, the exaggeration is toned down but still fundamental for creating fluid, life-like characters.

Even more subtle uses of squash and stretch can be seen in digital hand-drawn films like Klaus (Netflix, 2019), where intricate shading and lighting blend with exaggerated forms to give a depth of realism that tricks viewers into thinking the entire film is 3D animated​.

Examples in 3D Animation

In 3D animation, squash and stretch is not only a stylistic choice but also a technical challenge. One of the best-known examples is Pixar's bouncing ball in their animation shorts. The key to mastering squash and stretch in 3D is maintaining the volume of the object or character—whether it's an organic shape or a rigid object like a robot.

A more advanced application of squash and stretch in 3D can be seen in animations involving cloth simulation or character rigs, where deformers are used to create exaggerated motions that still respect the object's natural volume. Tools like Maya, Blender, and Cinema 4D provide rigging systems that allow animators to control these deformations dynamically.
See another concise but useful analysis of a shot from the Open Movie “Sprite Fright” by Frame by Frame Animation :

Why Do We Need Squash and Stretch?

Squash and stretch makes the impossible feel plausible. Without it, animation would feel stiff and lifeless. Imagine watching a bowling ball fall with no change in its shape as it hits the ground—it would look unnatural, as if it were sliding, not falling. The squash at the moment of impact and the stretch as it recoils gives the viewer the visual cues they need to understand the ball's weight and speed.

Character Structure and Squash and Stretch

Squash and stretch can do wonders for both realistic and stylized characters. Here's why.

Maintaining Volume

A common mistake when applying squash and stretch is failing to maintain the character’s volume. Even as a ball squashes down, its overall mass should remain constant. Otherwise, you risk making the object feel like it’s changing weight mid-motion, which can be disorienting for the viewer.

The key is to balance the deformations. For instance, when a character’s body stretches in a leap, it’s not just about making them taller—portions of their body might get thinner to ensure the total volume stays intact.

Enhancing Emotions and Actions

Facial expressions also rely heavily on squash and stretch. By squashing a character’s face during extreme emotions—whether it's a shocked reaction or a fit of laughter—you can exaggerate their emotional state in a way that feels more engaging.

Creating Believable Motion

Motion is at the heart of animation, and squash and stretch helps to create a sense of acceleration, deceleration, and the physical properties of an object in motion. Whether it's the subtle recoil of a character's face after a big jump or the dynamic stretch of a character's limbs during a fast sprint, this principle helps define how characters interact with the world.

Common Mistakes and How to Avoid Them

Over-Exaggeration: Finding the Right Balance

One of the most common pitfalls for beginners is over-exaggerating squash and stretch. While animation inherently thrives on exaggeration to convey life and motion, there is a fine line between enhancing a character’s dynamism and breaking the viewer's suspension of disbelief. Squash and stretch, when applied excessively, can make objects or characters feel too elastic, reducing their believability. For instance, in realistic animations or games where physics plays a significant role, stretching a rigid object like a bowling ball to a comical extent can break the immersion. To avoid this, animators should always consider the context of the animation style and medium. A cartoon might allow more room for exaggerated stretches, but in a semi-realistic context, restraint is essential.

How to Avoid It:

• Observe real-world physics: Before applying squash and stretch, think about how the object or character would behave in real life. A bouncing rubber ball will exhibit a significant amount of squash and stretch, while a bowling ball should have almost none.
• Study animation styles: Different genres and styles permit varying degrees of exaggeration. Refer to classics like Looney Tunes for extreme use of squash and stretch, and contrast that with Pixar films, where the technique is used sparingly to enhance, not dominate, the narrative.
• Layer your animation: Begin by animating without squash and stretch, focusing solely on the base movement. Once you're satisfied with the core action, selectively apply squash and stretch to areas where it can enhance the motion without overwhelming it.

Volume Retention: A Key to Consistency

Another frequent mistake is failing to maintain volume consistency during squash and stretch. The principle of squash and stretch doesn’t mean an object or character can change its mass; rather, it deforms while maintaining the same volume. When squashing a ball, for instance, the width increases while the height decreases proportionally. If volume is not retained, objects may appear to magically expand or contract, which disrupts the sense of weight and physicality.

How to Avoid It:

• Use reference guides: Set up visual aids or grids in your animation software to help you check whether the volume is consistent during deformation. Many 3D animation programs have built-in tools to monitor changes in an object's volume over time, helping you spot discrepancies early.
• Manual volume checks: For traditional 2D animation, it helps to trace over your animation frames, ensuring that despite squashing or stretching, the overall surface area remains consistent. Keep the proportion of width and height balanced.
• Practice geometric shapes: Start by practicing squash and stretch on simple geometric shapes, like spheres and cubes, where the volume is easier to track. Then, apply that understanding to more complex models like characters.

Object Material and Properties: Squash and Stretch Specificity

One of the more subtle mistakes animators make is applying the same degree of squash and stretch to all objects, regardless of their material properties. The extent of squash and stretch should vary based on what the object is made of. For instance, a water balloon might stretch and squash dramatically, but a rock would only display subtle changes, if any. Misapplying this principle, like stretching a solid metal object too much, can break the illusion of the object's material properties.

How to Avoid It:

• Understand the material: Study how different materials react under force. Soft and flexible materials like rubber or cloth will squash and stretch more dramatically, while rigid materials like glass or stone won’t deform as much.
• Apply secondary actions: Instead of forcing squash and stretch on a rigid object, consider adding secondary actions like vibrations or subtle deformations. For example, a heavy object like a bowling ball may not stretch, but it can compress slightly upon impact with a surface, giving it a realistic sense of weight.
• Use real-world references: Animators should study video footage of real objects interacting with the world. For instance, observe how a bouncing basketball deforms differently from a plastic water bottle or a metal canister. Understanding the inherent properties of each material will make squash and stretch applications more intuitive and convincing.

Matching Squash and Stretch with Motion

It’s also important to match the degree of squash and stretch with the speed and intensity of the motion. Slow-moving objects should show little to no squash and stretch, whereas fast-moving objects, especially those experiencing rapid changes in direction or force, can benefit from more extreme deformation. Mistakes often happen when animators over-apply the technique in situations where the speed or energy doesn’t warrant it, leading to unnatural motion.

How to Avoid It:

• Base deformation on speed: Use the speed of the object or character as a guideline for how much squash and stretch to apply. For example, a character making a quick leap will require more stretch at the height of their jump, while a slow-motion walk might only need subtle squashing in the feet.
• Animate motion first: Always animate the core motion before adding squash and stretch. That way, you can ensure the primary action feels natural and grounded. Squash and stretch should only serve to enhance what’s already there.
• Ease-in and ease-out: When applying squash and stretch, make sure the transitions are smooth. Abrupt changes can make the movement feel jerky or robotic. Use easing techniques to ensure that the squash/stretch transitions into and out of the base shape in a fluid, believable way.

Using Squash and Stretch for Emotional Effect

Finally, squash and stretch can be used to convey emotion, especially in character animation. Characters can be stretched or squashed not only to reflect physical forces but also emotional states. Over-squashing a character in moments of frustration or sadness, or stretching them in moments of excitement or shock, can add layers of personality and depth to the animation.

How to Avoid Overdoing It:

• Tone and context: Always consider the overall tone of the scene. Over-exaggerating emotional squash and stretch in a serious or somber moment can feel jarring and out of place. In contrast, in a lighthearted, comedic moment, the same technique might work perfectly.
• Subtle vs. extreme: Match the degree of squash and stretch to the emotional intensity of the scene. Subtle stretches might be appropriate for mild surprise, while extreme stretches can emphasize shock or joy in a more exaggerated animation style.

Squash and stretch is an indispensable tool in animation, but like all tools, it requires careful and thoughtful application. By understanding the principles behind it—volume retention, material specificity, and motion dynamics—animators can avoid common pitfalls and use squash and stretch to bring their characters and worlds to life in ways that feel both dynamic and believable. It's all about finding that balance between exaggeration and realism, ensuring that your animation retains its intended tone and style without losing coherence or believability.

Alan Becker sums it up nicely in his short video on Squash and Stretch

Learning Squash and Stretch: Tips and Resources

Mastering squash and stretch is about practice and observation. Start with simple exercises, like animating a ball bounce with varying weights—light rubber balls, bowling balls, or even soft objects like a flour sack. Adobe Animate and Blender both offer robust tools for experimenting with squash and stretch in both 2D and 3D.

Books like "The Animator's Survival Kit" by Richard Williams and "Disney Animation: The Illusion of Life" by Thomas and Johnston are indispensable for animators looking to hone their skills.

Conclusion: The Impact of Squash and Stretch on Animation

Squash and stretch is the secret sauce that makes animation pop. It provides weight, elasticity, and believability to characters and objects, no matter their form. As animators, whether we're working in 2D, 3D, or even mixed media, the ability to wield this principle effectively will elevate our work and immerse our audience deeper into the worlds we create.

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