Resorcinarenes (resorcinol-aldehyde tetramers) of appropriate structures have been shown to change the hydro- and oleophilicities of a variety of surfaces. The phenomenon results from attachment of the rim of the bowl-like molecules to hydrophilic surfaces. Hydrophobic (alkyl) and oleophobic (perfluoro alkyl) "legs" attached to the bowls then determine the immediate surface property. Amounts required to modify surfaces are only between 2 and 10 mg m(-2) treated, and there is evidence of multilayer formation. Penetration of surfaces by a variety of liquids has been studied and cannot easily be understood as a function of density, viscosity, or surface tension.