Saucepans can be made out of lots of materials: stainless steel, copper, aluminium, glass, cast iron.
Which one is best?
Well, to answer this, we need to think about the job we require in a saucepan to do. We have in it some food that we wish to heat, and it is sitting on a heating element of some sort.
The heat is only occurring on the bottom of the saucepan, and often only on a relatively small area. That is, whether we have a gas or electric cooktop (induction heating is a separate topic on its own that I’ll discuss later), the heat is only being applied at the points where either the flames or the elements come into contact with the bottom of the saucepan.
Now what we want from our saucepan is for this heat to spread right across the cooking area. In other words, we want the entire bottom of the saucepan to become hot, as well as the sides. so we want a substance that conducts heat well.
So which of the materials mentioned above is the best conductor of heat? The answer is cast iron. This may surprise you, but it won’t surprise anyone who does a lot of camping, for which cast iron cooking implements are very common. The reason they are common for camping, is that a campfire is obviously less well controlled as a cooktop, and so you need something that will conduct heat very quickly to all parts of the material.
This is the reason that cast iron is such a common material for brake discs. for brake discs to work well. They must lose it to their surroundings quickly, and the better the conduct of heat it is, the more quickly this happens.
For years the best motorcycle brakes on the market were Brembos, which were Italian brakes that used cast iron discs. You could easily pick them, because after only a couple of days of not being ridden, the discs would develop a coating of surface rust. Of course, the reason that steel, particularly stainless steel, is more widely used these days than cast-iron for most things, is that it is more corrosion resistant. There are also other reasons, connected with superior mechanical properties, but I won’t go into it here.
So cast-iron pans are the best. Next best is copper, which is why it is common for premium saucepans to see them built with a copper base plate, and stainless steel sides.
The worst of the lot is glass, as it is a very poor conductor of heat. Glass saucepans look nice when they’re sitting in your cupboard, but they are terrible to cook with – I remember my mother had a set, and it was almost impossible to heat milk in them, without seeing a burn mark on the bottom of the saucepan in the exact shape of the element.
What of aluminium? I’m not sure how aluminium stacks up in the heat transfer stakes, but I personally wouldn’t use them, as there has been a suggestion (which is in my view at least feasible) that their use may be associated with the early onset of Alzheimer’s disease.
But that’s a story for another day.