On Jan 12, 9:37*am, croy wrote:
On Fri, 11 Jan 2013 06:49:29 -0500, Norminn

wrote:
It's hard to imagine the rubber feet of the strainer causing
abrasion of the porcelain...

Not hard for me to imagine. *When deliberately lapping
surfaces, it's common to use a softer material as a tool to
lap the surface you want lapped. *The grit in the lapping
compound embeds in the softer material, and abrades the
harder material.

The rubber feet on the drain rack could well pick up
abrasive material from cleansers, and act much like slow
grinders on the porcelain.

--
croy

The rubber feet on the drain rack could well pick up
abrasive material from cleansers, and act much like slow
grinders on the porcelain.

+1