Contact Angle Measurements on Aircraft Coatings

Contact angles using water were measured
on five coatings used on aircraft. These
coatings are very uniform spatially but do
exhibit hydration, meaning their contact
angle changes as a function of exposure to
the vapor of the test fluid (i.e., water).
Therefore each contact angle was measured
as a function of time, with t = 0 corresponding
to the first contact of the water with
the dry surface. Two contact angles can be
identified: an initial angle and a steady-state
angle. These surfaces equilibrated in about
15 seconds, as can be seen from the representative
graphs of contact angle versus time
presented below.