We show these processes schematically in Figure for isothermal and non-isothermal growth. In Figure we depict the substrate in the initial state with a thin catalyst film. Just before the initiation of CNT growth, i.e. when the catalyst film has been heated to the growth temperature (for example 850 ºC) under a reducing environment (typically 5-10% hydrogen balanced with an inert gas such as argon) a portion of the catalyst film dewets and forms particles (Figure ). Film dewetting has been found to follow sigmoidal kinetics and depending on the reactants (i.e.