I adore my 18/10 stainless-steel cookware because it’s sturdy and conducts heat well. What does the “18/10” designation refer to?
Marla Shepard, via email, None
Byron Bitar, founder of A Cook’s Wares, replies: Your prized 18/10 stainless-steel pans have four main metal components: iron, carbon, chromium, and nickel. Iron is soft, so carbon is added to make it hard (steel is an alloy of iron and carbon). Your pans have about 0.1% carbon. Carbon steel rusts and corrodes easily, so chromium and nickel are added to give the metal chemical durability. Your pans contain 18% chromium and 10% nickel, the two numbers in the stainless-steel formula.
Chromium bonds with oxygen, forming a protective layer on the surface of the pans so they won’t rust (stainless steel is any type of steel containing at least 10% chromium). Nickel is harder than iron, and very resistant to corrosion, rust and stains. It gives the pans a silvery appearance.
There are three key features of 18/10 stainless steel that make it well suited for cookware. It’s soft enough to be molded into the shapes of pans and utensils; it can hold acidic foods and cold and hot liquids for long periods of time without corrosion; and it’s chemically very stable, enabling it to withstand extreme temperature changes without deforming or deteriorating.
Stainless steel is a very poor conductor of heat. Carbon steel conducts heat three times quicker than stainless steel, pure aluminum conducts heat ten times quicker, and copper conducts heat twenty times quicker. For that reason, good stainless-steel pans have a conductive core of carbon steel, copper or aluminum. Sometimes the core is in the pan’s base and sides, usually it’s just in the base.