We contend here that the predictions of these theories and the
extent to which data are consistent with them are somewhat
fortuitous, but not right. This is not a new contention and is
essentially the same point that has been made weakly several
times in the past. Pease3 did not, in 1945, directly question these
theories but clearly suggested the ideas behind the questioning.
Bartell directly questioned18Wenzel’s theory in 1953 and showed
that the contact angles of droplets on surfaces containing
roughnesswithin the contact linewere identical to those of smooth
surfaces. Extrand16 showed that the three-phase structure at the
contact line, not the liquid solid interface beneath the droplet
controls contact angle. He prepared surfaces with chemically
heterogeneous islands that exhibited contact angles identical to
surfaces without islands when the islands were in the interior of
the contact line. We have stressed19 24 that contact angle and
hysteresis are a function of contact line structure and that the