Working in an old house, where a bathroom is being transfered to the room next door! The current wall backing on to the bathroom was sin quite bad shape, so the joiner that was working at the house has boarded up and skimmed a new wall (multi tasking obviously). He's done quite a tidy and straight job. However, the finish is a dead shiny slippy finish (Is that PVA?) Im a bit concerned about tiling on it (300x300), will it be ok once its primed? Any ideas guys?