PANCAKES

The equilibrium state of a microdroplet spreading spontaneously on a solid surface is usually expected to be a compact monolayer if the liquid is nonvolatile, i.e., if the temperature is well below the 2-dimensional critical temperature T2C. More recently, it has been shown by de Gennes that this picture does not hold any more close to the wetting transition, where the initial spreading tension S0 tends to vanish. Thicker, stable layers are predicted, the famous ''pancakes'', the thickness of which diverges at the wetting transition. There is another case where the monolayer picture fails: some liquids composed of amphiphilic molecules, although they do not wet the substrate, build an autophobic film on it. On hydrophobic surfaces, this film is a perfectly organized bilayer of molecules. We give examples of the three situations, with the following nicknames: ''French pancake'' for the compact monolayer, ''Swedish pancake'' for the bilayer, ''American pancake'' for the thick film.