I recently built a basking ledge for my 4 month beardie out of styrofoam which i then grouted and used water based polyurethane to waterproof. I set up his new enclosure yesterday and when i went to check the temp on the basking spot witb my infrared thermometer i got a reading of 144° while the surrounding area still under the heat lamp was omly 112°. Could it be the dark color of the ledge (dark grey) or maybe the polyurethane? I have a 100w bulb would lowering the wattage resolve this ? What other materials can i use that are less heat absorbent?