Ceramic charcoal cookers are known for their ability to retain heat and one of the benefits of this property is that the outside of a ceramic cooker will not get as hot as the outside of a metal cooker. Unfortunately, overzealous owners and dealers sometimes make the claim that the outside of their ceramic charcoal cooker stays cool to the touch. Of course this is rubbish, so we thought we'd take a few actual measurements to give you the real scoop on this topic.
First of all, what do various manufacturers actually say on the matter?
Kamado Joe — "The ceramic base and lid of our grills can get very warm, but incidental touching will not cause a burn injury."Our testing has shown that some of these claims are a bit exaggerated. First we checked the surface temperature of a large Big Green Egg. We brought the cooker up to 400° F by keeping the vents fully open, then closing the vents down as the cooker approached 400° F. We left the cooker at this temperature for 30 minutes, then took readings of the surface temperature with an infrared thermometer. What we found was that at the lower portion of the lid near the rim, the temperature was 190° F. At the top near the chimney, the temperature was at rim, 230° F. As a point of reference most humans begin to feel pain when they touch a liquid or solid at 115° F. We couldn't keep our hand on the top for any length of time at all. Just a quick brush was all we could manage. We let the cooker continue at this temperature for a total of 2½ hours and the temperature at the top of the lid was 245° F. Trust us. This is hot.
Imperial Kamado — "It's Safe. Outside surface may be touched while cooking."
Big Green Egg — "The innovative ceramic material (now based on space-age technology) keeps the outside surface far cooler than any gas grill" and "Surface stays cooler and is safer around children than metal grills".
Primo — "And the outer surface stays at a safe, warm-to-the-touch temperature."
Kamado — "The exterior tile is safe to touch."
The next test we ran was with a Komodo Kamado 22" OTB refractory cooker. This cooker is probably one of the best insulated "ceramic" cookers around as the walls are comprised of a two-layer sandwich, of which one layer is intended to insulate and keep the heat in the cooker. We let this cooker sit at 400° F for 2½ hours. The surface temperature of the Komodo Kamado varied from 110 degrees at the base of the dome to 160 degrees at the top near the upper vent. You could leave your hand anywhere on the Komodo Kamado's dome for at least a few seconds.
So clearly, the surface temperature depends on the material, thickness and construction of the walls of the cooker. Some of them get quite hot, too hot to touch, while others remain cool enough that you can actually touch them for a few seconds. Needless to say, however, it's best not to find out how got your cooker is via an unplanned experiment. No ceramic charcoal cooker will remain "cool to the touch."