Compressibilities (Cs) and excess surface areas (ΔAM) are calculated for mixed films of asphaltenes and resins and asphaltenes combined with different commercial demulsifiers from Langmuir measurements. Both attraction and repulsion is observed between asphaltenes and resins, depending on the composition of the film. High molecular weight demulsifiers present in an asphaltene film increase the compressibility and the repulsion in the film, which is important for the demulsification process of water and crude oil emulsions.