What kinds of stains are these and how do I remove them?

Question

I recently bought an All-Clad D3 4qt sauce pan. I've used it exactly twice. I boiled water with the pot filled 2/3rd to 3/4ths of water and then once it was boiling I boiled spaghetti noodles in it for 10 minutes.

Today, after the 2nd use, I see these marks,

They do not come off with soap and a sponge. I tried vinegar as suggested by the all-clad site but it had zero effect.

I also have a 2qt pan from the same line that I've had over a year and used countless times. It has no similar marks.

What are these marks? Can they be cleaned off and if so how? Did I get a bad sauce pan? It was fairly expensive so I'm disappointed it has these marks.

Answer 1

According to their website, you pan is coated with a polished stainless steel coating. As stainless steel is relatively inert, I doubt if normal use in a domestic kitchen would cause this via food splashes etc. Certainly I would not expect to see this on such a new pan.

It is difficult to tell from the photo, but it looks as if the coating has almost dissolved or peeled off. If you run your fingernail over the marks can you feel any "lip" or does more of the coating come away? These marks could well be due to a failure during the coating process along with poor quality control.

Unless the pan has been abused and somehow been exposed to chlorine, hydrochloric or sulphuric acid, I would return this for replacement or a refund.

Answer 2

"Stainless" steel keeps rust-free by creating its own ultra-thin protective layer when exposed to oxygen. Manufacturers usually process pots and pans under such conditions that the layer is invisible. But on polished steel, it can also become bluish-iridescent, as you see it on your pot.

I am a bit surprised to see it in that place, because it usually happens with exposure to extremely high heat. It is commonly seen on welds, or sometimes on the bottom of pots which were overheated while empty. But whatever the conditions which produced it, it seems that you got it on your pot.

The problem is purely cosmetic. You can continue using the pot without any concerns for either the safety or the quality of the food you make in it. Since it is not a deposit on the surface, but part of the metal body itself, you cannot clean it off. I think that it can be polished away if you have polishing machines (it would be next to impossible by hand!), although I haven't heard of it being done for pots.

I would continue using it as-is. It is a perfectly good pot, and after all, a pot is a functional item, not decoration.