  During the spreading of a liquid over a solid substrate, the contact line can
stay pinned at sharp edges until the contact angle exceeds a critical value. At
(or sufficiently near) equilibrium, this is known as Gibbs' criterion. Here, we
show both experimentally and theoretically that for completely wetting volatile
liquids there also exists a dynamically-produced critical angle for depinning,
which increases with the evaporation rate. This suggests that one may introduce
a simple modification of the Gibbs' criterion for (de)pinning, that accounts
for the non-equilibrium effect of evaporation.
