  If we pull out rapidly a metallic frame out of a surfactant solution, we
arrive at a "young" soap film with relatively simple features, as noticed first
by Lucassen. The weight of the film is equilibrated by a vertical gradient of
surface tension. At each level, the local solution concentration equilibrates
with the local monolayers. A detailed analysis of the young films was started
by us in 1987. We present here an approach which is more illuminating a) the
concentration profiles decay exponentially at large heights, with a
characteristic length in the range of meters b) the surface is protected up to
a different (larger) height c) we also review the dynamic requirements. The
surfactant must reach the surface in a time shorter than the free fall time of
a pure water film.

Soft Condensed Matter