If surface tension depends on temperature, a fluid motion will be induced along a free surface with a temperature gradient. This is a common phenomenon in many materials processes, characterized by small volumes of liquid metal, and the presence of free surfaces. Examples are crystal growth and welding. In floating zone crystal growth the technological problem is to obtain a stable, steady thermocapillary driven flow in a drop of liquid Silicon. The paper Levenstam & Amberg (1995) describes the instabilities in such flows and discovers a new path to oscillatory motion, and also a new instability mechanism. This research is theoretical/numerical but close contact is maintained with material science and experimentalists, an example is in the paper by Levenstam, Amberg, Tillberg and Carlberg (1990). Work on welding has recently started.