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.