Vessil Sink Drain Alignment

Ok, so now I'm ready to install the vessel sink on the lavatory cabinet. The grid drain is installed, but the drain is off plumb. I loosened and re-tightened the grid drain to make sure it wasn't an installation mistake.

In order to make the drain plumb, I'll have to shim up the back of the vessel sink by 1/4 inch.

Questions:

1. Is this acceptable, or should I be taking the sink back to the supplier?

2. I'm assuming the drain must be plumb in order to install the p-trap - is any degree of out-of-plumb acceptable?

3. If it is Ok to shim up this much, will there be any problem with the attachment of the sink. The sink is attached with silicone sealant - will a bead of silicone that thick provide secure attachment? I'm assuming I'd have to leave it for several days for the silicone to cure. Then a bead of silicone around the base will hide the irregularities.

Thanks,
Steve

The sink should be plumb. And the tailpiece should also be plumb...vertical. Usually, it is possible to "rock" the drain assembly in the sink so the tailpiece is plumb...before final tightening of the nut underneath.

I tried "rocking" the drain before tightening the nut underneath. The drain remains significantly off plumb. The only solutions I can see are either (1) shiming the sink 1/4"; or (2) returning the sink for a new one.

Steve