Plateau’s Rules

The Belgian scientist Joseph Plateau (above) made painstaking observations of soap films in wire frames. From these observations (and his own intuition) he developed a set of rules which govern the equilibrium of soap films and foams:

• Three soap films meet at angles of 120 degrees.
• The films form a curved triangular channel known as a Plateau border.
• Four Plateau borders meet at angles of 109.6 degrees to form a vertex.