On June 3, 1985, Otl Aicher was sitting together with us in what used to be Johannes Potente’s workshop in Brakel.

Spread out on the workbench before us, we had all the door handles that had been designed by Johannes Potente and then mass-produced later on. Aicher challenged us to find the common denominator of all these designs.

To live up to our reputation as makers of hand form design, we pointed out the grasping properties of each model, for example the spot where the thumb would always find its place. Otl Aicher picked up each door handle and examined it, then took up his pencil, drew a circle on a sheet of paper and wrote “thumb stop” next to it. Somewhat encouraged, we ventured that the same principle would apply to the index finger, since in the process of grasping, the hand spreads outward with the thumb and the index finger performing a kind of pincer movement. All handles were examined once more, and the result of this second test was defined as “index finger rest”. Otl Aicher again took his pencil and sketched the new tactile mark. Once these first two hurdles had been taken, many more definitions emerged. Above all, volume and convexity were found on many handles. Otl Aicher listened to us, sketched symbols of volume and convexity and wrote the definitions we had formulated next to them.

In the following years we were at first the laughing stock of the industry whenever we were asked the question which would be the best grip and replied by quoting the four principles of grasping, and then asked the questioner to take hold of a handle himself. Meanwhile though, the ergonomic principles of grasping have entered scientific textbooks and the feature pages of leading newspapers.

1. Thumb stop
The thumb always seeks a direction. Traces of this search have already been found on the earliest prehistoric hand axes. Many objects for grasping are distinctly thumb-oriented.

2. Index finger rest
The index finger is always looking for direction. The guide of the hand finds the way, and let the other fingers follow.

3. Support for the palm
The hand, as a unit, requires a support. The thumb and the index finger explore the environment. Then the entire hand is engaged in grasping. This is where the heel of the hand needs support, which is the only way to apply the hand’s force.

4. Volume
Hands do not like grasping into the void. They prefer to be guided around spherical shapes. They need volume. People unconsciously reveal this basic need when idly playing with treats for the hand, mostly colourful egg-shaped stones.