On Food and Cooking

As we’ve seen, heat conduction in a solid
proceeds either by the movement of energetic
electrons, or by vibration in crystal structures.
A material whose electrons are mobile enough
to conduct heat well is also likely to give up
those electrons to other atoms at its surface:
in other words, good conductors like metals
are usually chemically reactive. By the same
token, inert compounds are poor conductors.
Ceramics are stable, unreactive mixtures of
compounds (magnesium and aluminum
oxides, silicon dioxide) whose covalent bonds
hold electrons tightly. They therefore transmit
heat slowly by means of inefficient vibrations.
If subjected to the direct and intense heat of
the stovetop, ceramics can’t distribute the
energy evenly. Hot areas expand while cooler
areas do not, mechanical stresses build up,
and the utensil cracks or shatters. This is why
ceramics are generally used only in the oven,
where they encounter only moderate and
diffuse heat, or are applied in thin coatings on