Cookware Materials Explained: Steel, Cast Iron, Aluminium and Non-Stick

Cookware is sold on adjectives — professional, premium, restaurant-grade — attached to a small number of materials whose behaviour has been understood for a century. Once you know what each material does with heat, the marketing becomes noise and the choice becomes a matter of matching a pan to the cooking you actually do.

This guide explains the materials and the terms printed on the box. It ranks nothing and names no brands.

Heat conduction vs heat retention

Two different properties, constantly confused, and between them they explain nearly every difference in how pans behave.

Conduction is how quickly heat moves through the material and spreads across the base. High conduction means fast response and even heating: turn the hob down and the pan follows. Copper and aluminium conduct well; stainless steel conducts poorly.

Retention is how much heat the pan stores, which depends mostly on mass. A heavy pan holds enough energy that dropping food into it does not collapse the temperature — the property that gives a good sear and steady frying. Cast iron retains superbly and conducts slowly, which is exactly why it browns well and burns things if you are inattentive.

Neither is better. Sauces and anything needing control want conduction; searing and shallow frying want retention. Most kitchens need one pan of each rather than a matched set of either.

Stainless steel and what the grade numbers mean

The two numbers describe the alloy: roughly 18% chromium and 10% nickel in 18/10, or 18% chromium and essentially no nickel in 18/0. Chromium provides corrosion resistance; nickel adds resistance and a brighter finish, and also makes the steel non-magnetic — which is why 18/10 pans need a magnetic layer added to work on induction, while 18/0 works directly.

Stainless is durable, non-reactive with acidic food, dishwasher-tolerant and effectively permanent. Its weakness is conduction, which is why a bare stainless pan produces hot rings and scorching. Quality stainless cookware is therefore always clad, with aluminium or copper doing the heat work and steel providing the surface.

Food sticks to stainless when the pan is under-heated or the food is moved too early; that is technique rather than a defect, and it is the price of a surface that will outlive the kitchen.

Cast iron, enamelled and bare

Cast iron is mass. It heats slowly and unevenly, then holds temperature better than anything else in a domestic kitchen, which makes it excellent for searing, shallow frying, baking and long braises.

Bare cast iron needs seasoning — a polymerised layer of oil built up through use — which gives a naturally slippery surface and protects against rust. It is reactive with acidic food until well seasoned, dislikes prolonged soaking, and is essentially repairable: a neglected pan can be stripped and re-seasoned indefinitely.

Enamelled cast iron replaces seasoning with a fused glass coating, so it is non-reactive, easy to clean and suitable for acidic braises. The trade-off is fragility: enamel chips if knocked or subjected to thermal shock, and a chipped interior generally ends the pan's useful life.

Both are heavy, which matters more than buyers expect — a full casserole is a two-handed lift, and weight is a genuine constraint in a small kitchen, as discussed in buying for a small kitchen.

Aluminium and hard anodising

Aluminium conducts heat exceptionally well and is light and cheap, which is why it forms the core of most clad cookware even when you never see it. Raw aluminium is soft and reactive with acidic ingredients, so it is rarely used as a bare cooking surface.

Hard anodising is an electrochemical process that thickens and hardens the aluminium's natural oxide layer, producing a dark, much harder, non-reactive surface. It is a treatment of the metal itself rather than an applied coating, so it cannot flake — though many hard-anodised pans also carry a separate non-stick coating on top, which can.

The practical result is a light, responsive, durable pan. The limitation is that hard-anodised surfaces are generally not dishwasher-friendly, and the treatment does not make the base magnetic, so induction models need a bonded disc.

Non-stick coatings: types, wear life and care

Non-stick is a consumable surface applied to a metal pan, and treating it as a wear part rather than a permanent feature explains everything about how to buy and use it.

The common families are fluoropolymer coatings, typically PTFE-based, and ceramic coatings derived from silica. Fluoropolymer coatings are slicker at the outset and have a defined maximum service temperature published by the manufacturer, above which they degrade — which is why heating an empty non-stick pan hard is the single most damaging thing you can do to it. Ceramic coatings tolerate higher temperatures but tend to lose slipperiness sooner with use.

Coating life depends on heat, utensils and cleaning rather than on time: metal tools, abrasive scourers, dishwasher cycles and high dry heat all shorten it. Because the surface is consumable, non-stick is the clearest case in the kitchen for the arithmetic in cost per use — a cheaper pan replaced periodically can beat an expensive one used carelessly.

Carbon steel and copper

Carbon steel behaves like a lighter, thinner cast iron: it seasons the same way, tolerates high heat, responds faster because there is less mass, and is the traditional material for woks and professional frying pans. It rusts if left wet, and it will warp if thin and thermally shocked.

Copper is the best conductor in common use, giving unmatched responsiveness for sugar work and delicate sauces. It is reactive, so cooking surfaces are lined with tin or stainless steel, and the lining is the wear part — tin linings can be renewed by a specialist. Copper is heavy, expensive and needs polishing to stay bright, which makes it a specialist choice rather than a general one.

Cladding and layer counts: tri-ply and beyond

"Tri-ply" means three bonded layers, conventionally stainless steel on the outside, an aluminium core in the middle and stainless on the cooking surface. Five-ply and seven-ply add further alternating layers, usually to combine aluminium's conductivity with copper's or to increase total core thickness.

Two questions matter more than the number. How thick is the conductive core, since a thin core in a five-layer pan will underperform a thick one in three? And is the cladding full, running up the walls, or only a disc bonded to the base? Disc-bottomed pans heat the base evenly but leave the walls poorly heated, which shows up when reducing a sauce or cooking anything shallow.

Weight is again the honest proxy, for the reasons set out in how to judge product quality online: metal has mass, and a pan that feels light for its size has less of it somewhere.

Hob compatibility, especially induction

Induction heats by inducing a current in the pan itself, so the base must be ferromagnetic. Cast iron, carbon steel and magnetic stainless work directly; aluminium and copper require a bonded magnetic disc, which manufacturers add specifically for this purpose.

The reliable check is a fridge magnet: if it grips the base firmly rather than falling away, the pan will work. Two further details are worth knowing — a base smaller than the hob zone may not trigger it, and a warped base will heat unevenly on induction in a way it would not on gas, so flatness matters more than on other hobs.

Gas and radiant electric hobs accept anything, but with less control at the low end, and hob type is one of the constraints worth fixing before shopping, as in how to choose kitchen appliances.

Matching material to what you actually cook

Choose by task rather than by set. Eggs, pancakes and delicate fish want non-stick, accepted as a periodically replaced item. Searing, shallow frying and anything that benefits from a crust wants cast iron or carbon steel. Sauces, reductions and anything requiring control want clad stainless. Long braises want enamelled cast iron or a heavy clad casserole. Boiling water wants whatever is cheapest and lightest.

Most households are well served by three or four pans chosen this way, which will outlast several matched sets bought on appearance. How long each should reasonably last is covered in how long should things actually last.