Why flannel keeps ice unmelted but people warm?

Answer 1

Flannel acts as an insulator, keeping things at the same temperature. It slows down heat transfer with the surroundings. If what you wrap it in is colder than the surroundings, then it will take longer to warm up. If what you wrap in it is warmer than the surroundings, it will take longer to cool down. Ice can stay cold and people can stay warm. The same concept is true for the common thermos bottle - you can keep Hot Chocolate hot in it or cold juice cold.

Note that in the case of people, we are constantly producing body heat from our metabolism so all the flanel has to do in order to keep us warm is to slow the heat transfer to a rate that is less than or equal to the rate at which our bodies are producing heat.

Answer 2

Flannel traps air within its fibers, providing insulation against cold temperatures. This helps to keep people warm by retaining body heat and blocking out the cold. However, when used around ice, the insulation properties of flannel prevent external heat from reaching the ice, thus slowing down the melting process.