According to the directions with the Insulbrite I bought first, it said to put the shinier side to the hot side so I put the shiny side to the outsides of the potholder so both sides could be used. The Insulbrite that I bought last month said it didn't matter which side was used.. There was a definite shiny side so I still put that side to the heat.
Also when i made these potholders, I quilted them some so they would stay flat plus it made them more decorative. They are so much fun to make. As insaid in an earlier post, I basted my batting layers together and inserted them after I turned the potholder right side out. It was easier for me and since I was quilting them the batting doesn't shift.