THERMOGRAM OF A HEAT RETENTIVE PLATE (Click link above)
The colors show the thermal gradient that keep the plate from breaking due to thermal shock. Temperatures as high as 230 F can be reached at the center (With just one minute preheating) while the rim does not get hot for easy handling. The photo was taken during the cooling down phase and does not reflect the maximum temperature reached. obviously, if you do not want it that hot, you have the option of preheating for less than a minute.