Differential forms on free and almost free divisors

We introduce a variant of the usual Kahler forms on free and almost free divisors and their deformations, and show that they enjoy the same depth properties as Kahler forms on isolated complete intersection singularities. Using these forms, it is possible to describe analytically the vanishing cohomology in families of free divisors, in precise analogy with the classical description for the Milnor fibration of an ICIS, due to Brieskorn and Greuel. This applies in par- ticular to the family of discriminants of a versal deformation of an unstable map-germ.