3. Layer the bags one by one and secure with clothespins to keep them from shifting. Heat iron to medium high. Put a layer of baking parchment or wax paper over your ironing board and on top of the stack of plastic bags. Iron from the center outward, being careful to iron each section thoroughly for 30 to 60 seconds. Let cool, then flip the whole thing over and iron the other side. Let the paper cool until it comes easily off the surface, and check the fabric to ensure it’s fully laminated. If not, iron again.