Objects & Craft
Pans are three metals answering the same question differently
Cookware behaviour is metallurgy. How quickly a pan heats, how evenly it holds that heat and how it reacts to food all follow from what it is made of.
Everything below about cookware materials comes from what actually happens rather than from what is supposed to.
What holds up in practice
- Conductivity spreads heat sideways; mass holds it steady when food goes in.
- Reactive metals interact with acidic food, which changes flavour and appearance.
- Seasoning is a hardened layer of polymerised oil, not a coating applied at the factory.
Two properties that matter
Thermal conductivity determines how quickly heat spreads sideways across the base, which is what prevents hot spots over a burner. Thermal mass determines how much heat the pan holds, which is what stops the temperature collapsing when cold food is added. Copper and aluminium conduct extremely well, so they respond quickly and follow the heat source closely.
Cast iron conducts poorly and holds an enormous amount of heat, so it heats unevenly and then stays hot regardless of what is added. Almost every design decision in cookware is a way of combining these two properties in one object.
Why pans are laminated
Stainless steel is durable and unreactive and conducts heat badly, which is why a plain stainless pan burns in rings. Bonding a layer of aluminium or copper between stainless layers gives the conductivity of one metal and the surface of the other.
Over years, a disc bonded only to the base spreads heat across the bottom but not up the sides, which matters for sauces and for tall pans. Fully clad construction carries the conductive layer up the walls, which is more expensive and behaves better. Thickness matters as much as construction, since a thin clad pan still lacks the mass to hold temperature.
Reactivity and what it does to food
Aluminium and cast iron react with acidic ingredients such as tomatoes, wine and citrus, which can affect colour and taste. Anodised aluminium has a hardened surface layer that reduces this, and stainless steel is essentially unreactive.
A well-seasoned iron pan is protected by its polymerised oil layer, which acidic cooking will gradually strip. Copper is highly reactive and is therefore lined, traditionally with tin and now usually with stainless steel. This is why long acidic simmering is generally done in stainless or enamelled pans rather than bare iron.
Seasoning is a chemical layer
Seasoning forms when thin films of oil are heated past the point where they polymerise into a hard, bonded layer. That layer is what gives cast iron and carbon steel their release properties, and it builds with use rather than arriving complete. Thin applications repeated many times produce a durable layer, while a thick application produces a sticky one that flakes.
Soap does not destroy seasoning, since the layer is polymerised rather than merely oily, but abrasive scouring does.
Rust appears where seasoning is broken and water is left standing, which is why these pans are dried immediately after washing.
Coatings and their lifespan
Non-stick coatings are surface treatments with a finite life, and they degrade with heat, abrasion and time. High dry heat is particularly damaging, and manufacturers set maximum temperatures for their coatings that are easily exceeded in practice. Guidance on the safe use of various coatings differs between countries and has changed over time, so following the current manufacturer instructions is sensible.
Room to room, a coated pan is a consumable in a way a steel or iron pan is not, and treating it as a lifetime object leads to disappointment. Enamelled cast iron is different again, being a glass layer fused to iron, which is unreactive and chips rather than wearing away.
Handles, bases and the hob
Handle attachment is a common failure point, and riveted handles generally outlast spot-welded or screwed ones. Materials that can go from hob to oven expand the usefulness of a pan considerably, and plastic handles usually cannot. Induction hobs require a ferrous base, so aluminium and copper pans need a steel layer to work on them at all.
Underneath it, a base that is not flat rocks on a solid hob and heats unevenly, and thin pans warp when heated empty or cooled suddenly. Matching pan diameter to the heat source avoids both wasted energy and a ring of overheated food at the edge.
The takeaway
Match conductivity and mass to what you cook, keep acid out of bare iron, and dry the pan the moment it is washed.
A room that is used will always beat a room that is finished.
Questions readers ask
Why does my stainless pan burn in the middle?
Stainless conducts heat poorly, so unless there is a bonded aluminium or copper layer spreading it, the pan reproduces the shape of the burner.
Does washing cast iron with soap ruin the seasoning?
No. Seasoning is polymerised oil bonded to the metal, not a film of grease. Abrasive scouring and leaving the pan wet are what cause problems.
