Just checked my Insul-Bright wrapper. Here is what it says : Insul-Bright is the ideal insulated lining for many projects. It consists of hollow, polyester fibers neddlepunched through Mylar. The hollow fibers resist conduction while the reflective Mylar resists radiant energy. The energy, hot or cold, is reflected back to its source. In other words, you would want the shiny mylar side out for hot pads.