  In order to characterize very weak adhesive surfaces, we have developed a
quantitative test inspired by the Johnson, Kendall, and Roberts adhesion test
for soft adhesives, which relies on the formation and then the rupture of a
capillary bridge between the surface to be tested and a liquid bath. Both the
shape and the kinetics of breakage of the capillary bridge for various coatings
put into contact with liquids of various viscosities and surface tensions have
been studied. Several pull off regimes can be distinguished. For low pull off
velocities, a quasi-static regime is observed, well described by capillary
equations and sensitive to the hysteresis of the contact angle of the fluid on
the coating. Above a critical pull off velocity that depends on the fluid
viscosity, a dynamic regime is observed, characterized by the formation of a
flat pancake of fluid on the coating that recedes more slowly than the
capillary bridge itself. After the breakage of the capillary bridge, a small
drop can remain attached to the surface. The volume of this drop depends on the
dynamical regime and is strongly affected by very small differences between the
coatings. The aptitude of this test in characterizing very weakly adhesive
surfaces is exemplified by a comparison between three different perfluorinated
coatings.
