Well the setup doesn't get super hot right away, but I think if left on for a more extended time, such as when a new student first uses a grain magnifier or if they are trying to figure out how best to place the image on the easel, or test different magnification of the image, or practicing dodging and burning certain areas, the enlarger can potentially get hot to the touch. A 40w opal photo bulb would probably work pretty well. Right now a 150w bulb is installed as it was the last photobulb size in the darkroom, all the rest are the double pin type bulbs. I have not had any students use it yet as I installed it at the end of the day.