Methods of Heat Transfer

Conduction: the transfer of heat through solids. When the kiln is being fired kiln shelves gather and then release heat during and after the firing. The heat is transferred directly through the solid kiln shelf, posts and other pots on the shelf. When the heat source, whether it be electricity, gas, wood, coal, or any hydrocarbon based fuel, is turned off, the overall kiln temperature drops but the shelves and other kiln furniture act as a thermal reserve which still transfers its depleting heat to the pottery resting on the shelf. Some materials transfer conduction heat more efficiently than others. Anyone who has mistakenly picked up the end of a hard brick exposed to high heat has experienced burning conduction heating firsthand. There is still a great amount of heat stored within the hard brick which takes a while to dissipate. Conversely, picking up a soft brick, which is formed with air pockets throughout the structure, will not transfer heat readily and can be handled at the opposite end if one end is extremely hot.

Convection: the process by which heat is transferred through the movement of air. This method of heat transfer can be felt when opening a hot oven. Air molecules are heated from the heat source and then move about the kiln, heating the interior of the kiln, shelves and pots.

Radiation: When heat is transferred through the kiln by energy waves it is called radiation. When a kiln is heated the greater the thermal mass in the kiln from bricks, shelves, posts and pots, the greater the radiant heat that is transferred to every object in the kiln. After the heat source is turned off radiant heat is still affecting all the objects in the kiln.