I am about to fit a small cloakroom basin and the supplied chrome slotted waste comes in just two parts; the main waste and a large metal flanged nut, and crucially, no large washer. Given that the flanged nut would have to mate directly with the ceramic basin, I can't help thinking there should be a large washer between the basin and nut.
Could someone please confirm if this is the case, or do I just put in a bead of sealant?