Hearth Cooking Method: Using Radiant Heat
The warmth you feel on your face as you sit in front of a fire is radiant heat. The heat is thrown of by flames and by embers. In this digitial photograph of a chicken being cooked within a clay pot the source of the radiant heat as a combination of flame and ember is clear. The flames are yellow and orange, and the embers are purple. Different fires, and fires in different stages, will throw off heat with differing combinations of fire and embers. What is not obvious to the beginning hearth cook is that one often finds that the ember portion of the fire is more important than the fire portion in providing steady radiant heat to foods cooking in front of the fire on the hearth.
Anything set in front of the fire absorbs heat. The heating is from the side. From long experience cooking on a gas, electric, or induction stove-top we are used to the idea of heating foods from the bottom. When cooking with radiant heat the food heats from the side.
In this photograph, we can see where the radiant heat falls on the pot — it is on the portion of the pot illuminated by the flames. That heat is a combination of radiant heat flowing out fromthe embers and radiant heat flowing out from the flames. This is a comparatively shallow fireplace. The back brick wall is hot and it will also be contributing radiant energy to the cooking pot.
This clay pot is narrower at its bottom than at its waist. That slope from the widest portion of the pot to the bottom is near the embers. This is a classic shape for a clay pot, and while this particular pot was not intended as a cooking pot, it shares with cooking pots a shape that is uniquely efficient on the hearth. It’s shape maximizes the absorbsion of radiant enery falling on its side.
The cooking speed can be controlled a couple ways. Assuming a steady fire, then the closer to the fire the pot is placed the faster it cooks, and the farther away from the fire, the slower it cooks. In practice, because radiant heat increases, or decreases, by the square of the distance, a small change in position can make a big difference in the speed of cooking. A fraction of an inch away from the fire the air is over one-thousand degrees F., but three feet from the fire nothing would cook. A few inches from the fire is usually a safe place to start — 4 inches — 10 cm.
While one can turn the pot if one wants, it is rarely necessary as the convection currents within the liquid will adequately distribute the heat.
If a few embers were pushed up against the bottom of the pot it would cook faste. If the pot were pulled back further away fromth