I was installing a bathroom sink drain assembly recently. Due to the
sink material, I couldn't use putty under the drain flange. I didn't
feel like using silicone under it, partly because any leak would just
flow into the drain chamber and really only prevent the sink from
maintaining a steady basin of water with the stopper engaged. Also,
if I needed to change the drain assembly out, it'd be easier not to
have something clinging under the flange.
So, I sprinkled some ground cinnamon around the wet flange, and all
leaking ceased instantly. It was somewhat amusing.
I'm sure calcium in the water will further infiltrate the cinnamon
seal with time.