First we would like to point out the following: In the following text we assume that you are right-handed. If you are left-handed you will have to exchange all 'right hand' and 'right' for 'left hand' and 'left' and vice versa. Once you have had a little more practise, you will quickly develop your own technique. In the beginning we suggest for you to follow our instructions.
First of all you need to fill the balloon with some air (figure 1). We recommend using a pump since it is exhausting to blow up a balloon. The balloon should never be blown up completely since sculpturing will use up some of the volume. It depends on the model / the molecule how much air needs to be in the balloon and will become easier to judge with growing experience.
Figure 1: A balloon with little air.
Now the balloon can be twisted at any point as shown in figure 2. In order to do this the balloon has to be squeezed together with the thumb and forefinger of the left hand and the right end of the balloon has to be twisted with the right hand. Make sure to hold on to the balloon to keep it twisted in the right position, otherwise the knot will open up again.
Figure 2: A balloon can be twisted at any point.
To hold the knot take the left balloon bubble between your little finger and the ball of the thumb of the left hand (figure 3). Now the knot can't open anymore. Further knots can be pushed up.
Figure 3: The first, not fixed bubble has to be held together.
After making a twist, simply bend the balloon in order to make a simple loop. Create another twist opposite the first one. Pull the loop and twist it (figure 4). The created knot can symbolise a free pair of electrons.
Figure 4: A simple fold twist is easy to make.
After creating three twists, fold the balloon, so that two bubbles end up next to each other (figure 5).
Figure 5: Three bubbles are needed for the extended fold twist.
Both left bubbles are pulled a little bit and then twisted (figure 6) to secure the foldtwist.
Figure 6: Now the bubbles get twisted.
For the pinch twist you need one small, round bubble, that - as explained above - is pulled away and twisted to lock (figure 7). The pinchtwist is a very important knot that is used to separate balloons.
Figure 7: Turning a pinchtwist.
In order to cut a balloon at a certain position (e.g. because the sculpture is finished or the rest of the balloon isn't long enough to finish a sculpture), the last twist before separating has to be saved. There are two different possibilities to do this; in both cases you need the saved pinchtwist:
Both long ends right and left of the pinchtwist are bent upwards. Then the pinch twist is tied up so that two little round bubbles are created. These are twisted twice as shown earlier making the foldtwist (figure 8).
Figure 8: How to save a pinchtwist (1st possibility)
The pinch twist is divided into two equally sized halves that are turned against each other. Now both long ends, right and left of the pinch twist are turned upwards and the divided pinchtwist is twisted twice just like the foldtwist (figure 9).
Figure 9: How to save a pinchtwist (2nd possibility)
The pushthrough has several functions. On the one hand it serves to secure the extended foldtwist at a short end of a sculpture, on the other hand it helps to secure a newly added balloon. In this way a triple compound can be shown. The third bubble to be introduced is placed on top of the two already existing bubbles. Then those two are rolled over the third bubble. For reasons of clarity the third bubble is shown in green in figure 10.
Figure 10: The pushthrough looks harder than it is.
For the tuliptwist your finger might need to be moistened, since otherwise it might be too difficult to pull it out of the balloon. The moistened finger is pushed into the balloon with the mouthpiece of the balloon. How deep the finger is pushed depends on what you intend to do with this twist. After reaching the right depth, you grab the twist from the outside and push the balloon carefully off your inner finger. Then the balloon is turned at the twisted position (figure 11). Due to the static friction of the balloon this twist usually does not need further securing.
Figure 11: The tuliptwist needs some practise.