I use silicon sealant on basin wastes, but no washers.
Put a bead around the flange, to keep the water in the basin, then turn it upside down and fill the gap, do the nut up hand tight plus a pinch with the grips, and leave to cure.
Never leak, and hope you don't every have to take it out.
Put a bead around the flange, to keep the water in the basin, then turn it upside down and fill the gap, do the nut up hand tight plus a pinch with the grips, and leave to cure.
Never leak, and hope you don't every have to take it out.