Inbetweening/Cleanup

By Jeremy Falkowski

This tutorial will cover the steps in producing a quality inbetween/cleanup drawing. It’s important to become good at this skill, as inbetweening is typically the entry-level position at an animation studio. Even if you don’t have the materials listed below and are unable to do the practice inbetween, simply familiarizing yourself with the process will help you immensely when starting out at a studio.

What is inbetweening? Inbetweening involves taking two drawings and roughing in and cleaning up a line in the middle of those two drawings. Sounds simple enough, right? Well it’s not. The inbetween test I’ll be using with this tutorial is relatively easy, but when you get into detailed inbetween assignments like those given at the large studios, it will take you many tests, many hours, and many hand cramps in an attempt to get good at it. In my opinion, the difficulty of inbetweening/cleanup is a good thing. After all, you don’t want to be spending eight hours a day at an animation studio doing a mindless and tedious job, and as you’ll learn by the end of this tutorial, inbetweening is anything but that.

Even though an inbetween will only appear on screen anywhere from 1/24 of a second to 1/12 of a second (if the drawing is shot on two’s), every drawing counts and sloppy cleanup/inbetween work will be apparent. For one thing, the eye can see up to 30 frames a second so your drawing will be visible. Also, any errors that may seem small on your animation paper, will be magnified many times over and will become large errors when viewed on a movie screen. That’s why companies that really pride themselves on their animation will not accept an inbetween that is mediocre or just good. Each drawing counts and each drawing must be excellent.

For this tutorial, I’ll be using two key drawings of a leaf for the sample inbetween. If you would like, you can print out my two key drawings copy them onto your animation paper and do the inbetween along with me.(leaf1, leaf2) And of course you can always create your own key drawings and practice inbetweening them.

Leaf 1

Leaf 2

Materials: A carmine red col-erase pencil: it’s important that you get this exact color. Most studios’ ink and paint systems won’t pick up this color when the drawing is scanned in, so that only the final graphite line will be picked up, and not the underlying red drawing.

• A light table (if you don’t have access to one, you can purchase a portable light box at cartoon colour co. for $75, or if you are handy, you can build your own).
• A pencil sharpener. It’s very important to keep your pencil sharp at all times and most are around $10-$15 at an office supply store.
• Several sheets of animation paper. (Use the heavier animation paper from cartoon colour co. as the cheaper stuff is like tissue paper and is difficult to flip)
• Hole protectors. These are important because when you flip the paper, the holes will start to expand and rip and the drawings will begin to move around and the inbetween will be inaccurate.
• A kneaded eraser.
• A .3 mechanical pencil with .3 B lead (if you can’t find B lead, F and HB are acceptable alternatives).

All of the above supplies can be purchased at cartoon colour co. For a free catalogue, call them at (800)523-3665.

Preparation:
Arrangement on the peg bar: Let’s call the first key drawing "1" and the last key drawing "5" (the drawing with the end of the leaf turned up), and your inbetween will be number "3". Place drawing 1 first on your peg bar, and then place drawing 5 on top of that. Now place your blank sheet of animation paper, which will be the inbetween, on top. In the top right hand corner of each piece of animation paper, write the number of each drawing. Your drawings should look somewhat like
Figure 1.

Put your hole protectors on: Put your hole protectors on once the paper is on the peg bar, and use the protectors for both the key drawings and the inbetween. If you don’t have any hole protectors you can still do the exercise, but like I said, after a lot of flipping, the holes will start to expand and tear slightly and the drawings will begin to move around. This will result in an inaccurate inbetween. Another thing you’ll notice if you don’t have protectors is that the holes will be too big for the pegs and the drawings will keep falling off the peg bar while you are flipping. You don’t want to have to hold down the drawings while you are flipping. One hand should always be in position to flip with the other hand drawing. The hole protectors will help keep the drawings securely on the peg bar.

Turn your light table on: When working with the red pencil, the initial stage of inbetweening, you want your light table on. When you are applying your graphite line you want your light table off. Very experienced cleanup artists can do the majority of the inbetween without the light at all. But this takes many years of training your eye, and since the studios expect exactness, most people use the light during the initial stages.

Flip the key drawings: It’s important to flip your keys alone several times before starting any drawing to get a feeling for the action. It becomes particularly important when you have an entire scene to inbetween, say 10 or 12 key drawings, and you need to understand the action as a whole. 

How to flip?

• Begin by holding the left side of the top drawing (no. 3) with your thumb on top and the index finger and middle finger of your left hand underneath the drawing (assuming you draw with your right hand; if you draw with your left hand, hold the paper with your right hand). Then place your ring finger and pinky underneath the second drawing. There should be no fingers underneath the last drawing; it should stay flat against the light disc.
• Flipping should be started by seeing the bottom drawing first (drawing "1") by pulling the top two drawings up a bit. Don’t lift the bottom drawing at all. Just let it stay flat against the animation disc.
• Next bring the top two drawings down and see the top drawing, the inbetween (drawing "3").
• Then lift the top drawing up with your thumb and index finger and push your middle finger down on the middle drawing (drawing "5") as far as possible in order and see the middle drawing. Try to push the middle drawing as far as you can with your middle finger so that it lays flat against the disc when you view it. You want to view all of your drawings when they are flat not when they are at an angle to you.
• So in review, it’s bottom drawing, top drawing, middle drawing, bottom drawing, top drawing, middle drawing, bottom drawing…etc…etc. Becoming a good flipper takes some practice, and you want to get fast at it so that you can see the movement of the drawings and not just see the individual drawings. Your paper should start to crinkle on the side. Don’t worry about this. The camera won’t pick up these crinkles.

Helpful tip: if the key drawings you are inbetweening are near the top of page, hold the paper at the top left hand side; if the drawings are near the middle, hold the paper near the middle left side; and if they are near the bottom hold the drawings near the bottom left hand side. You do this in order to see the drawings as easily as possible. If your drawings were at the bottom and your flipping near the top, it’s difficult to see them. This is common sense, but it’s still a good reminder. 

Inbetweening is broken up into three stages: first drawing the line in with your red col-erase pencil; second, pushing back the red with your eraser, and third, drawing in your final graphite line.

Drawing the inbetween, Part 1: Drawing in the "rough" line

There’s no magic formula to inbetweening. It might be nice if there was, but then again it would be boring. Each inbetween requires problem solving on your part in order to get that drawing in the middle of the two keys. For my sample inbetween of the leaf I’ll show you some principle techniques that apply to all inbetweens and some that I’m using for this specific inbetween test. Again, each inbetween calls for a different solution and you have to figure out which solution will help you the most in your drawing.

One last reminder before we start. You should be constantly flipping your three drawings during these exercises. After every mark you make with your red pencil, flip the drawings to see if everything is working. Your drawing will get very crinkly on the side you flip. That’s ok. It should.

Figure out your major arcs
One very important principle in animation is that everything moves on an arc—everything. Wave your hand in front of you. Your fingers are moving in an arc like motion. Some arcs aren’t as obvious as this, but everything does move on arcs. There are ‘u’ shaped arcs, ‘n’ shaped arcs, there are very large arcs, and there are very subtle arcs. It all depends on the action. A pitcher who’s throwing a baseball would have a very large arc with his arm, while someone turning their head would have a more subtle arc movement. Therefore if you are handed two drawings to inbetween, your inbetween must follow an arc. If the action just moved on a straight line, it would look robotic and unnatural. 

Start by arcing and inbetweening points:
To draw the arc, pick a point on one of the keys and make a red dot there (draw this on your inbetween drawing, not your key drawing). Then go to the next key and find that corresponding point and make a second dot on your inbetween drawing. At this point you should have two red dots on your inbetween paper. Next, figure out how these two points are arcing by flipping your key drawings and looking at how the "points" are arcing. Then connect the two dots of your inbetween by drawing that arc. Finally draw a third dot in the middle of that arc. 

For example, I chose the top of the stem as an arcing point. I made a point there for the first drawing, then looked at the next key, found the top of the stem, and made a second point on my inbetween sheet. Then I flipped the two keys and looked at how the top of the stem was arcing. I then drew in that arc between the two points, found the center or inbetween point on that arc, and drew in my third dot. When I’m inbetweening points, it also helps me a great deal to put a line through both of my key points in order to better see the inbetween point. See Figures 2.1 and 2.2.

Figure 2.1

Figure 2.2

How many points should you arc? Well it depends. For the leaf drawing, I chose these points: the point where the stem meets the leaf, the top of the stem, and the tip of the stem. I arced all of these points. See Figures 3.1 and 3.2. Notice in this drawing that since I had inbetweened the top and bottom of the stem, I was able to lightly rough it in in the drawing. I chose these points because they were distinct points of reference for the two keys. It was also obvious for me to see how they those points were arcing. You don’t have to put million of points all over your drawing and start arcing them. 

Figure 3.1

Figure 3.2

Arcing and inbetweening shapes:
Another excellent technique for figuring out your arcs is to start breaking the key drawings up into shapes and seeing the shape's movement. For this example, I broke up the broad part of the stem into a large oval with a small triangle left over at the top. I then drew an oval and triangle for both keys on my inbetween drawing, arced the two ovals, and then drew in the inbetween oval. So I basically had three ovals on my inbetween drawing. To find the exact inbetween of the oval, I drew points at the top and bottom of the oval and then found there inbetween using the first technique I talked about. The triangle simply fit on top of this oval, so I didn’t really need to make points for it. One thing you’ll notice is that when you get the really large shapes down accurately, the smaller details and shapes, like the triangle, can just be eyed in. With the inbetween points and shapes my drawing is starting to take shape. See Figures 4.1 and 4.2.

Figure 4.1

Figure 4.2

Extend lines off of points to inbetween major landmarks. Earlier in the tutorial I was mentioning how it is helpful to put a line through your key points to better see the inbetween. Well, making lines or slashes at key areas is also extremely helpful in inbetweening other landmarks. For instance on each side of the leaf there are a few jagged edges. At the tip of each jagged edge I extended a line off of it, one for each of the keys, and then simply drew a line in the middle. You could use the point technique, but at this point you’ve already got most of the drawing fleshed out, and getting exact points will just be too confusing, tedious, and time consuming. Look at Figure 5.1 and 5.2 to see how I used simple slash lines to see where the inbetweens fit in. I used various numbers and letters to illustrate where I put the slashes. For instance A, B, and C. ‘A’ represents a line extended from one of the main jagged edges on one of the keys. ‘C’ represents that same jagged edge on the other key drawing. I extended these lines out pretty far and I was simply able to eye the line inbetween these two extended lines, which was ‘B’. I drew in that jagged edge there. I did the same with the other numbers represented on the sample drawing.

Figure 5.1

Figure 5.2

I’ve also drawn in the middle vein line of the leaf since I knew where the top of it started and I knew where it ended from the earlier inbetweening, so I simply eyed the two key drawings to see how the vein was moving and then tried to approximate the placement of the middle vein in the inbetween drawing. Later on, as I’ll show in this tutorial, I’ll clarify this line, by checking and rechecking distances, but for now, it just helps me to get a rough estimate of the major parts of the inbetween.

At this point my rough drawing is really coming along. I’ve figured out how the leaf is arcing, I’ve got the major shape of the leaf, the placement of the stem, the inner vein line and a couple of the jagged edges.

Clarifying and checking your drawing

Diffusing the light: At this stage, I like to diffuse the light somewhat. To do this, take your animation drawings off your peg bar and place two or three blank sheets of animation paper on the peg bar. Now take your drawings and place them on top of the blank sheets of paper. This will diffuse the light from the light table a bit.

Checking angles and distances: The stem as you saw was pretty much figured out using the inbetween points of the top and bottom of the stem from the key drawings. However a good way to check it, is to look at the first key drawing and see at what angle the stem is pointing, and then see how the angle has changed in the next key drawing. I usually like to think about it like a hand on a clock. For instance, in the first drawing, the stem is slightly past 12:00 and in the next key, the stem is around the 3:00 mark, so my inbetween should be at around 1:30. Also, look at the middle vein in the leaf. At what angle (or time) is that running along one key and how is that changing in the next key? Draw in the distance in your inbetween.

Look at how the leaf is angling away from the stem on the left side (viewer’s left side). On the first drawing, the line is steeper than it is in the second key drawing. Draw the difference in the steepness in your inbetween. The same with the other side of the stem.

The middle vein in the drawing breaks up the leaf into two nice shapes. Notice how in the first drawing, the left side from the vein is narrower than in the second key drawing. You have to draw in the distance. Notice how the middle vein itself goes from being fairly steep, to flattening out. Inbetween the difference in your drawing.

To get the inbetween of how the leaf curls up at the end, I simply guess that it would be about half the volume of the final key and then using the end point of the leaf that we inbetweened earlier, I drew it in.

I could go on and on,about the infinite minute differences in the key drawings--the different angles, distances, shapes, where parts line up, but you get the general idea from some of the above examples. The more ways you reference your two keys, the more accurate the inbetween will be.

Getting the small veins, other jagged edges and the rest of the details.

As you’ve been noticing, I’ve always been going from general to specific. I’ve been getting the major shapes down and carefully inbetweening the key points. The rest of the inbetween can be drawn by just using these established points.

Check and recheck the inbetween drawing: Make sure that you have everything that’s included in the key drawings, every little vein. Make sure you drew in that small hole in the leaf. Notice how the hole is slightly closer to the middle vein in the second key than it is in the first. This was a slight error on my part when drawing the keys, but these incongruities happen all the time in key drawings and you are still responsible for inbetweening the changes. So if on one drawing the hole is 1 mm from the middle vein and on the next it is .4 mm, it is your responsibility to put the inbetween .7 mm from the middle vein. Notice how the edges on the leaf changed somewhat. You have to reconcile these changes in your inbetween.

Make sure your volumes haven’t changed: One of the biggest mistakes that beginners make is that parts of their drawing start to either shrink or grow. In other words the volumes are changing. Keeping your volumes consistent, particularly your major volumes, is very important. One good way to check your volumes and your inbetween as a whole, is to take all of your drawings off the peg bar, take the two key drawings and align them as best as possible (neither one should be on the peg bar at this point), then place your inbetween on top and align it with the two keys. You can check your stem to see if it is the same size as the stem in the other keys, you can check the basic volume of the leaf, and so on and so forth.

Helpful tip: To test out your drawing, it many times helps to turn the two key drawings and the inbetween drawing over so that you are see the back side of them and then flip the drawings. It helps you see mistakes you otherwise wouldn’t see if you flipped with the drawings facing you. It’s the same theory with drawing. Many times holding your drawing up to a mirror or turning it upside down and holding it up to the light will show errors in the drawing which you otherwise wouldn’t detect.

Your final red drawing should looking something like Figures 6.1 and 6.2.

Figure 6.1

Figure 6.2

Remember when your drawing goes to be photographed, none of the red pencil marks will show up, so use the red to your advantage to help you. Don’t try to make a perfectly clean drawing, just to try to impress your supervisor. They’ll be more impressed if they see you thinking, if they see lots of marks, arcs, etc.

Drawing the Inbetween, Step 2: Pushing Back the Red 

You’ve completed the most important part in red. The graphite line obviously is important because it will be the line that shows up on the big screen, but it is more of the icing on the cake of the drawing. If you ask any animator, they’d rather work with a cleanup artist who can do a really excellent inbetween line and a so-so cleanup line, as opposed to someone who can do a so-so inbetween line and an excellent cleanup line.

Turn your light table off: Generally speaking, the red col-erase portion should be done with the light on and the cleanup portion should be done with the light off.

Push back the red: Take your kneaded eraser and roll it into a hot dog like shape. Then take it and put it on top of your drawing and roll it up and down on top of your drawing like a rolling pin rolls out dough. This technique is better than just erasing normally as it will keep you from erasing too much of the red pencil marks and it will erase everything evenly.

You want the heaviness of the red to be lightened a bit, but not so much that you can no longer see it. See Figure 7 for what the pushed back red drawing should look like.

Figure 7

Drawing the inbetween - Part 3: Drawing the Graphite Line

The thickness of the line: You want your graphite line to be the same thickness as the two key drawings. Look at your two key drawings and see how thick they are and try to emulate that in your inbetween line. If you were working on a cartoon like the t.v. show 101 Dalmatians where the style is very thick lines, you would want to make your inbetweens thick too, but if you are working on a Disney film, where generally the lines are pretty thin, then you want your cleanup line to be thin as well. Otherwise, when the line is projected many times bigger on a movie screen, the difference in line will become very evident.

When drawing the cleanup line, click on your mechanical pencil two or three times; a tip much longer than this will cause the lead to keep breaking since .3 is very thin and fragile.

Technique of drawing the line Go over the underlying red drawing with your mechanical pencil. Do not draw the graphite line with one continuous long line. You will just end up with a sloppy, wobbly and inconsistent line. What you should do is go through the line making small “scrubbing” strokes, flexing your thumb and index finger and moving your hand slowly over the page. Also when there’s shifts in the movement of the line, turn your animation disc so that you can draw the line in a comfortable and competent way with your hand. If you’ve ever watched a professional doing cleanup, they are constantly moving their disc around. Keep your pencil on the paper until you have to move the disc. Don’t make a single stroke, pick up your pencil and then make another stroke.

Your line should have a uniform thickness and weight. Make sure that your line doesn’t have thick areas and then thin areas right next to each other. Also, make sure that the line isn’t too light in an area and then darker in another area. Your line should have a consistent thickness and value. Erase away any little thread marks on the side of the line so that the line is clean. Remember, your line will be magnified many times over when it is seen on a movie screen, so really strive for a quality line.

Make sure all shapes are closed off. When your drawing is done, it is sent off into ink and paint, and if all of your shapes are not closed off, the paint will bleed out of the shape. So double and triple check to make sure everything is closed off and there are no openings where paint could bleed out.

Make sure you haven’t missed anything. When you get really detailed drawings to inbetween, it’s a common error to forget little small things to inbetween, like the light in someone’s eye, or the squiggle in their ear, or any number of other things. Make sure you’ve inbetweened everything.

Your final cleanup/inbetween should look something like what I have drawn in Figure 8.1 and 8.2

Figure 8.1

Figure 8.2

What now? 

Keep practicing: Like any skill, the more frequently you do something, the better you get at it. With practice, your drawings will improve and you will get faster. Create your own key drawings and inbetween them. There are also numerous examples of key drawings in “art of” books which you can copy and practice on.

Time yourself: Needless to say, the faster you can inbetween the better. The studios would rather have someone who can do a good inbetween in one hour than someone who can do an absolutely incredible inbetween in four hours. This is particularly true when it comes down to "crunch time" and everyone is under the gun to get the film completed. If you are unable to pump those inbetweens out, once production is done, you might be looking for a job somewhere else. Hey it’s a ruthless business. You can either accept that or deny it and see what happens. So when you are practicing inbetweening, write at the bottom of your paper when you’ve started the inbetween and then write down the time when you’ve finished. Try to get faster and faster. The ideal time on a fairly complicated inbetween is an hour. On this leaf inbetween, which is much easier, an experience inbetweener could do it a lot quicker than that.

During your first few inbetween tests, however, just concern yourself with technique and not speed. It could take you several hours per inbetween with your first few attempts. Believe it or not, that’s actually pretty average for a beginner. First focus on your competence with the basics of inbetweening and then worry about speed.

In Conclusion

You probably weren’t expecting such an involved process for something called inbetweening. I’ve written a lot, because there in fact is a lot involved in the process, but after awhile everything I’ve mentioned will be second nature to you. I’ve discussed the broad approach to inbetweening/cleanup using an example of a leaf to illustrate the points; however unless you are working on an animated musical about floating leaves, you will do very different inbetweens than the one I showed. I’ve provided you with the basic tools for inbetweening, but it’s your job as an artist to figure out when and how to use those tools for each individual inbetween.

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