Last week on my radio show I was asked whether cheaper brand cast iron saucepans might contain lead?
It’s quite a common question – there are also websites where people asked this question, which is no doubt the source of the listeners query. It appears to be based on the fact that often when people pick up cast-iron saucepans they feel particularly heavy – they therefore wonder whether the increased weight might be caused by lead.
As it happens, this fear is ungrounded. Cast-iron saucepans will not contain any lead.
Cast iron saucepans, as the name suggests, are made by being “cast” into a mould. The iron must therefore be heated hot enough not only to melt it, but hot enough so that there is time to pour it into the mould before it starts to cool and solidify. It is therefore heated substantially hotter than its actual melting point.
The melting point of iron is 1,535° C.
To cast it, they would therefore heat it no doubt several hundred degrees past this temperature.
Now, let’s look at lead. Lead melts at a mere 327.5 °C and by the time you reach the melting point of iron is very close to its actual boiling point of 1,750°C
So when the lion is hot enough to be cast, it would actually be above the boiling point of lead. So what little lead there may be in the iron, would simply boil out of it before it was cast, in exactly the same way that when you use beer or red wine in a recipe, the alcohol all boils out very quickly and you are left with the taste of the wine, but not the alcohol.
But there is one word of caution here. In years gone by lead was used as a pigment in paints. It is possible that very old saucepans with enamel coatings may have lead in their pigment. But most cast-iron saucepans are bare cast-iron, so this is not a problem.
So why do are people have this impression that cast iron feels “heavier” than stainless steel saucepans? The reason simply is that since cast iron is a more brittle metal than stainless steel, it must be made thicker to give it the mechanical strength. So it is simply this – cast-iron saucepans feel heavier because their thicker.