Film theory has become a recognized method for developing and designing chemical processes. It was developed in the chemical industry during the 1920's and became a staple of chemical process development during the 1950's.

Many believe film theory evolved from Prandtl's boundary layer theory. However, film theory arose in the chemical industry before Prandtl developed his boundary layer theory.

This presentation discusses the history of fim theory from its original hypothesis to its current usage.