  The behavior of thin liquid films is known to be strongly affected by the
presence of surfactants at the interfaces. The detailed mechanism by which the
latter enhance film stability is still a matter of debate, in particular
concerning the influence of surface elastic effects on the hydrodynamic
boundary condition at the liquid/air interfaces. In the present work, "twin"
hydrodynamic models neglecting surfactant transport to the interfaces are
proposed to describe the coating of films onto a solid plate
(Landau-Levich-Derjaguin configuration) as well as soap film pulling (Frankel
configuration). Experimental data on the entrained film thickness in both
configurations can be fitted very well using a single value of the surface
elasticity, which is in good agreement with independent measurements by mean of
surface expansion experiments in a Langmuir through. The analysis shows how and
when the soap films or dip coating experiments may be used to precisely and
sensitively measure the surface elasticity of surfactant solutions.
