When is short-range ''critical'' wetting not critical?

Recent interface Hamiltonian studies have posed the question: Can an instability mechanism, due to a variable interface stiffness, drive bare critical wetting transitions first order? We argue ''yes'' on the basis of a novel nonlinear renormalization group study allowing semiquantitative analysis in dimensions 1 < d less than or equal to 3. Fluctuation-induced first-order wetting occurs for d greater than or similar to 2.41 if the wetting parameter omega(T) is less than a tricritical value omega(t)(T). Crucially, in d = 3 (for relevant temperatures) we find omega(t) much greater than omega clearly enhancing first-order wetting as compared with earlier less conclusive studies.