What Is Cel Animation, And How Does It Work?

When you think of animation, you might instantly think of 3D design or CGI (Computer Generated Imagery). These are the staples of modern animation. However, there’s still room for the more traditional methods of animation. Cel animation forms the basis of all conventional hand-drawn or 2D animation and can be seen in almost every classic cartoon of the 20th century. Today, much of it can be automated by design software, but it still forms a critical part of the motion design work we do every day here at Frantic.

So cel animation has been around for a long time. The name comes from how Cel animation was traditionally done. Draft drawings were created during the planning process and then transferred onto see-through sheets. These transparent sheets were called ‘cels’.

They were called cels because of the materials used to make them. The earliest cels were made using flexible sheets of colourless and transparent plastic called Cellulose Nitrate. This material was highly flammable and degraded quickly with age – causing a yellow and wrinkled look and expelling toxic gasses in short periods of time.

The industry began using cellulose acetate, which lasted much longer but still degraded in time. The chemical composition released a vinegary scent that would later be labelled “vinegar syndrome”. If this vinegar substance had contact with the body’s moisture (nose, mouth, lungs, throat, etc.), it would cause irritation and illness. The industry kept evolving, and now the risk of vinegar syndrome is significantly reduced, not least because a significant proportion of cel animation is now done entirely on computers without cellulose in site.

Using a cel animation style, we designed and animated over fifty separate icons for Microsoft’s digital transformation series. With organic morphing motion graphics and flashy animated elements, the end result is a beautifully slick series of explainer videos rolled out across Microsoft globally.

The animation process involves hand drawing the various animated elements, scanning them, tracing the outlines, and then animating them frame by frame. It is a time-consuming process, but the end result is worth the effort. It feels organic and tactile and really helps to bring the icons themselves to life.

Cel animation is not a quick process. It takes time and can require a large team of people to complete the process fully.

Let’s first look at how cel animation was done for most of the last 100 years.

As with any animation, the first step is script development; from this, the storyboard can be created. It’s during this process that each shot is allotted its timing. The lead animator will then complete each character’s perspectives in different poses (noting the time on each sheet) – this is called the dope sheet, and everyone works from this.

The dope sheet tells everyone how long it should take for each movement and standardises the sequences of the cels. Junior animators will take the sketches of the poses and draw the in-between movements to create a smooth transition.

Once all of this has been approved, the sketches are passed onto the Inker. It’s the Inker’s responsibility to transfer the linework to the cels using black ink. Once the ink is dry, the Colourist will use cel paint to apply colour on the opposite side of the ink to be consistent, clear and crisp.

Whilst all of this is happening, there’s a team hard at work, creating the backgrounds for each scene. Because the scenes are often on screen for longer, they are usually more detailed and shaded. If the scene needs the character to move through it, then the background needs to be big enough for this movement to happen.

Once everything is complete, the cels and backgrounds are handed over to the photography team. Using the dope sheet, the photography team will layer the frame and take images of each one. When played at a speed of 12 or 24 FPS (Frames Per Second), these images will give you the impression of movement. This will provide you with the final animation sequence.

Before we get into this, we need to understand the trends in 2D animation and where that fits in the world of 3D and CGI. Even Disney, the advocate of 2D animation, has stepped away from hand-drawn 2D animation – their last 2D animated feature was Winnie The Pooh (2011) and has not announced plans to develop any more – yet.

On the other hand, Japanese animation still practices hand-drawn 2D animation – to stunning effect. A personal favourite, Studio Ghibli has become increasingly popular in the western hemisphere over the last few decades. They’ve even won an Academy Award for “Spirited Away”.

Cel animation as we know it has also undergone an evolution over the last few decades. Disney has been using digital technology within its hand-drawn animations since the late 1980s. The techniques and practices themselves are still used, but the application has changed.

Some animation studios still sketch by hand, but others (like us) have removed the need for pen and paper. We do this primarily because it is so much faster and easier to create work directly on screen. This also gives us better adaptability and the opportunity to experiment with different perspectives, proportions and styles in a more efficient way.

Most studios have moved on to using dedicated software packages that allow for higher productivity and produce seamless animation. There are many animation software packages available; each one has its own distinctive features and benefits.

It takes meticulous attention and dedication to create cel Animation. Because of this, it’s great to remember that cel animation has a lot of advantages over other forms. Advantages include:

• You can create strikingly organic looking pieces of imagery.
• This leads to a crisp style that is also unique and expressive.
• Detailed backgrounds through shading that gives warmth and charm.
• 2D animation can look 3D when executed correctly.

The cel animation method is a long process that can provide unique and distinctive styles that are instantly recognisable. Technology has come a long way over the last 100+ years of animation. Cel animation used to be dangerous, using combustible materials and unstable chemicals which caused physical harm to the human body.

Nowadays, the technique and process are still used and are as popular as ever, but western animation has taken to digital 2D and 3D animation in a way that no other areas of the world have. This does not mean that the process of Script → Storyboard → Sketching → Refining → Inking → Colouring → Photographing is no longer existent. In fact, quite the opposite is true; these are the foundations of animation and will continue to be in the future.