Vince wrote:
Recently had bathroom remodelled. The contractor was asked (politely)
to remove the "gunk" around the sink drain collar. He used his finger
nail to scrape the surface of the drain collar, which had a lacquer
finish. The (silicon) gunk remians.

When replacing that drain collar I will also want to remove the
silicon used as a sealant from the sink baisn where teh drain collar
sits. Any suggestions for a solvent for this purpose ?

The silicone hasn't bonded deep into the cultured marble, it's sitting
on the surface. Solvents may do more harm than good. I'd use my
finger nail and finish up with a rough towel.

R