The Basics of Cookware Materials
Though not necessarily decisive, knowing how well a material conducts heat is the first step in making a cookware choice. Heat conductivity is most important for pots, pans, and skillets used primarily on the stovetop, where heat-up speed and responsiveness to temperature changes can be critical and uniform heating is essential for preventing hot spots that burn food before it’s entirely cooked. In the oven, slow conductivity matters less and, combined with a material’s capacity for retaining heat, might even be advantageous.
- Far and away the most efficient heat conductor, copper has been hammered into pots and pans since caves were condos. Because it reacts with some foods and can be toxic in large amounts, copper cookware is lined with another metal. Traditionally that was tin. When the tin wore out, craftsmen replaced it, and copper cookware passed from generation to generation. “Retinners” are increasingly rare, and today copper cookware is more likely to be lined with durable stainless steel or less durable nickel. Being a poor heat conductor, a stainless-steel lining somewhat defeats the value of copper. Nickel, however, is about three times as efficient a heat conductor as stainless steel.
- Advantages: Nothing beats copper for preparing delicate sauces. It’s unsurpassed for quick, uniform heating, and a copper saucepan is so responsive to heat changes it can be taken on and off heat while cooking to maintain a precise temperature. These virtues are also useful in omelet pans, sauté pans, and other specialty cookware. That’s why most professional kitchens have a few copper pans. Going from stove to table, polished copper pans also make beautiful serving pieces.
- Disadvantages: Copper is costly. Copperware is heavy, particularly when lined with stainless steel. Finally, copper is difficult to maintain. It dents, scratches, and, above all, oxidizes (discolors). Fastidious cooks must polish copperware frequently. Others say the heck with appearance and learn to treasure the rustic patina copperware quickly acquires.
- Aluminum cookware comes in all price ranges and in various forms. A popular variant is “hard-anodized,” an electrochemical process that hardens the surface of aluminum and also changes its color to a pleasing charcoal gray.
- Another, less common form is cast aluminum, which is usually thicker than pressed-aluminum cookware. Expressed as “gauge,” aluminum thickness is counterintuitive. The lower the gauge, the thicker the aluminum. Because it’s confusing, few manufacturers mention their aluminum cookware’s gauge. Cast-aluminum cookware is usually six gauge. Cheap aluminum cookware can be as thin as 14 gauge. Other factors being equal (and they often aren’t), price is a guide to aluminum cookware’s thickness.
- Advantages: Second only to copper, aluminum is an excellent heat conductor. It’s also relatively lightweight and is generally dishwasher-safe. Thin aluminum cookware is inexpensive. Hard-anodized cookware is harder than steel and extraordinarily durable. Cast-aluminum cookware retains heat well and resists rust and warping.
- Disadvantages: Aluminum cookware is soft and porous, subject to dents and scratches. It stains, oxidizes, and reacts with certain foods, especially those that are high in acid, such as tomatoes. In its thinner forms, aluminum cookware also warps. Hard water can cause discoloration of aluminum cookware. Hard-anodizing eliminates all those problems but adds considerably to the price and adds a problem of its own: hard-anodized cookware is prone to discoloration in a dishwasher. Cast aluminum is heavy and not dishwasher-safe.
- Nearly as ancient a cooking material as copper and as likely to evoke nostalgia, cast-iron cookware occupies niches even in the most up-to-date kitchens. Grandma’s cast-iron cornstick pan and Dutch oven become valued heirlooms.
- Cast-iron cookware can also be glazed with a thin coating of a form of glass that, when applied to metal, is called enamel.
- Advantages: Although it conducts heat poorly and thus takes a while to get to cooking temperature, cast iron distributes heat uniformly and retains heat extraordinarily well. That means it’s superb for browning, frying, braising, stewing, slow cooking, and baking. It’s also inexpensive, naturally nonstick, and lasts forever. Because it is smooth and hard and comes in gleaming colors, enameled cookware adds beauty to cast iron’s virtues and goes from stove to table, where it looks good and keeps second helpings warm.
- Disadvantages: Cast iron is heavy (think: pumping iron). It must be seasoned with shortening and baked before its first use and then coated with oil or cooking spray after each hand cleaning to prevent rust. It reacts with acidic foods; however, that can also be a good thing. (To read why, see the section on health considerations below.) Cast iron also absorbs the flavors of foods and some cooks fervently believe that the browned crusts of a previous batch of muffins impart a wonderful flavor and that built-up caramelization in a cast-iron pan improves the taste of seared meats and poultry. Enameled cast iron can chip.
- An alloy, stainless steel combines iron with as many as eight other metals, principally chromium (for rust and corrosion resistance and durability) and nickel (for additional rust resistance, hardness, and high-polish capacity). Cookware-grade stainless steel has 18 percent chromium and either 0, 8, or 10 percent nickel. Thus, stainless-steel cookware is designated as either 18/0, 18/8, or 18/10, with rust resistance and polish–and price–rising along with the nickel content. Because it’s already in a pricier range, 18/10 cookware is usually thicker to appeal to the market’s high end. Similarly, 18/8 is usually thicker than 18/0.
- Advantages: Because it’s smooth, stainless steel is easy to clean and maintain and is dishwasher-safe. (Quality stainless-steel manufacturers, however, plead for hand washing to maintain polish and to prevent a discolored film that results from harsh detergents.) In addition, stainless-steel cookware is hard; resists scratching, denting, and warping; and, depending on thickness, is extremely durable. Because it’s a carefully crafted alloy, it resists corrosion, rust, and (naturally) staining and is nonreactive to food. If the cookware is 18/8 stainless steel or, especially, 18/10, it also takes and holds a high polish, or mirror finish, which not only looks nice but is stick-resistant.
- Disadvantages: A poor heat conductor, stainless steel is subject to hot spots. That’s why some manufacturers add a copper or aluminum disc to the bottom of pots and pans. (Bottoms of cheap cookware sometimes are sprayed with copper, a dubious improvement.) Stainless steel designated as 18/0 can be subject to rust. Overheated stainless steel can acquire a rainbowlike discoloration, which requires a stainless-steel cleanser to remove.
- Because no cookware material is ideal, top-end manufacturers laminate or bond various materials to maximize materials’ advantages. These multi-ply constructions have cores of pure aluminum or copper all the way up the sides of a pot or pan. Interiors are usually stainless steel or nonstick. Exteriors can be stainless steel, copper, aluminum, or hard-anodized aluminum.
- Advantages: Multi-ply cookware delivers superior all-around performance. Because it’s costly to make and therefore will be affordable only to high-end consumers anyway, manufacturers also go all out in the beauty department.
- Disadvantages: Price.
- Once scorned by professional chefs, nonstick has been improved to the point that few chefs or cooks would forego its advantages today, particularly when it comes to using skillets and cooking certain delicate foods such as fish. Nonstick is a coating. The quality of the coating, the number of layers, and whether it has been “bonded” to the cookware all affect nonstick’s performance and durability. Because nonstick brand names proliferate, the most reliable guide to a particular coating’s capabilities and limitations is the cookware manufacturer’s advice.
- Advantages: As its name implies, nonstick releases foods more easily and also cleans more easily. The best, bonded nonsticks won’t be damaged by metal utensils and are extremely durable.
- Disadvantages: Cheap nonstick wears thin quickly and scratches easily, creating spots where food sticks and rust develops. Better nonstick is more scratch-resistant and durable but, like cheap coatings, can require the use of nylon, plastic, or wood utensils. Even the best nonstick generally cannot go into an oven heated to more than 350 degrees F. All nonstick cookware needs to be hand washed.
- Despite anxieties about various cookware materials being hazardous to health, for the most part there is no scientifically established cause for these fears.
- Aluminum: People ingest about 10 milligrams of aluminum daily, mostly from food. Cookware contributes only 1 or 2 milligrams to that total. The World Health Organization says adults can consume 50 milligrams or more daily without harm. That said, as a precaution it is better not to cook with worn or pitted unlined-aluminum pots and pans or to store food, especially leafy vegetables and acidic foods such as tomatoes, in aluminum containers. Hard-anodized aluminum cookware presents no health hazards.
- Cast Iron: Because of the ubiquity of processed foods, residents of developed countries are more likely to be iron deficient (anemic) than to ingest too much. Some health authorities, therefore, advise using cast-iron cookware. Still, even employing cast-iron cookware exclusively would not provide an adult with enough iron, so iron-rich foods are essential.
- Copper: While small amounts of copper contribute to health, large amounts can be toxic. That’s why unlined copperware is restricted to specific uses. Whipping egg whites in a copper bowl, for example, results in a creamier, more stable foam. And stirring risotto or polenta in a copper pot means more uniform heating, while the traditional wooden stirring utensil minimizes copper infusion. Copperware lined with nickel can affect people allergic to nickel.
- Stainless steel: Stainless steel designated as 18/8 or 18/10 contains nickel, which can affect people allergic to nickel.
- Nonstick: Because they are chemically inert, materials used to manufacture nonstick cookware coatings are harmless. Leaving an empty nonstick pan on high heat, however, can cause it to release irritating or even toxic fumes if the pan heats to about 650 degrees F.