On Fri, 04 May 2012 09:21:12 -0700, Dwight
wrote:

We have a 23 year old Kohler cast iron kitchen sink that we have taken
good care of - dont let coffee residue stand in the sink, etc.

Now we are getting brown-gray stains that do not come off with Soft Scrub.

Do you have recommendations for methods or materials that we might try?

Thank you very much.

Dwight Gibb

For me? After a sink that many years old, I would call a pro.

They can restore a sink in look like new, serviceable condition.

It only takes an hour or two for the fix. Looks better than new.