I am sorry Tibbrix, but I do not agree with your instructions. To clean a stainless steel sink, use Barkeepers Friend on a sponge (not a scouring ball or any abrasive pad), and dry with a paper towel or microfiber cloth. From the Kohler website: - Always apply stainless steel cleaner/polish with a nonabrasive cloth or sponge, working with, not across, the grain. - Do not use steel wool, wire brushes or abrasive sponge pads. - Cleaners containing chloride are not recommended. If used, rinse the surface immediately to prevent corrosion. From the Franke website: Never use steel wool to clean your stainless steel sink. Persistent stains, including rust, can be removed with a variety of mild non-abrasive stainless steel cleaners such as FrankeâÂÂs Inox cream, Autosol Shine, and others. Always rinse thoroughly after using any cleaner. As a sidebar, and I am sorry to contradict Hollysprings whose posts I always think are excellent, I have had 2 Silgranit anthracite sinks in previous homes with hard water, and neither ever showed mineral spots. This is one of the leading reasons why people choose Silgranit sinks over stainless steel. This post was edited by Mrs_Nyefnyef on Mon, Sep 22, 14 at 8:42

After talking with the installers and my husband it looks like my husbands wedding ring might have made the marks when he was putting it back into the box. I inspected it when it came then he put it back in the box. He then tested a small area that won’t be visible and the ring really marks the sink up very easily. I will call Elkay and Quality Bath when they open this week and I’m waiting for Astonish to arrive on Tuesday. Hopefully that’ll do the trick or the company will have an idea of how to clean it up.

Most likely contamination, but stainless can of course corrode as well if exposed to certain conditions (that’s why there are thousands of different alloys). Most stainless is sold to ASMT/ASME standards stipulating the chemical composition, but what some are pointing out is that there is an allowed range for each alloying element and generally Asian manufacturers alloy low to maintain a low cost. A 304/304L SS from brand x is not necessarily alloyed as high as a 304/304L from brand y. The chemical composition, even within the allowed min/max range for the same alloy will have an impact on the corrosion resistance. Still, I think this is contamination and should come out. If not, you can remove it mechanically and the steel will reform the chromium oxide layer.

After getting the sink installed I'm regretting not purchasing a self-trimming apron front sink instead. When the contractors cut the cabinet, it left a small gap around the sink edges (and a few chips too). The contractor says they'll cover it with scribe molding so you won't see it, and hopefully that will resolve the issue. Wonder if other folks here with this sink or similar ones have had the same issue? Video showing the gaps around the sink here: https://1drv.ms/v/s!AmD8KjGtqRzxjohVhtoxF_BKmAksdQ?e=N315sO