  A new exponent characterizing the rounding of crystal facets is found by
mapping a crystal surface onto the asymmetric six-vertex model (i.e. with
external fields h and v) and using the Bethe Ansatz to obtain appropriate
expansions of the free energy close to criticality. Leading order exponents in
\delta h, \delta v are determined along the whole phase boundary and in an
arbitrary direction. A possible experimental verification of this result is
discussed.
