On May 4, 12:21*pm, 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

I'd try one of the rust stain remove products, like
CLR that you can get at HD, hardware store, etc
With rust stains, I've seen them just disappear
instantly when you put the product on.