Copolymers of chlorotrifluoroethylene and vinylidene fluoride, optionally together with tetrafluoroethylene, are dissolved in hexafluorobenzene. The solutions may be used for coating, casting films and for seaming metals and plastic films.ALSO:Substrates, e.g. of metals and plastics, may be coated with solutions in hexafluorobenzene of copolymers of chlerotrifluoroethylene and vinylidene fluoride, optionally together with tetrafluoroethylene. In Example (XI) a polyethylene substrate and a sand-blasted steel panel are coated with hexafluorobenzene solutions of chlorotrifluoroethylene/vinylidene fluoride copolymers.