Of cold and warm materials

When we touch different materials, we can feel different temperatures, even if these materials have the same temperature on the surface.

Wood or leather, for example, are “warm” materials and we feel a pleasant temperature when we touch them with our fingers or hands. This is not the case with stainless steel or aluminium, where we feel a certain coldness. Even though a thermometer would measure the same temperature on the materials. What is the reason for this contradiction?

This is an illusion of our perception that can be easily explained: It’s about the different thermal conductivity of each material. When touching or being touched, our hand gives off heat. This emitted heat is absorbed and conducted differently into the interior of the object. Sometimes more when we feel cold (because heat is drawn from us); sometimes less when we feel heat (because our hand hardly gives off any heat due to its low thermal conductivity).

This principle is used in house construction for thermal insulation, using the low or poor thermal conductivity of wood or foam to insulate the interior of the house well from the cold outside air.

In cooking, on the other hand, the thermal conductivity of metal is used so that the pot or pan heats up quickly.