The higher the wattage the more heat the iron will put out. I am trying to do toner transfer to a board that is more than twice the size of the surface of the iron. It is also 2 oz. and double sided. The board itself will suck heat away from the area I am trying to transfer the toner to. Has anyone done a board of this type and size with success? What Size iron in wattage did you use... THANKS for all answers....