THE PROBLEM: back of pressed image is not flat.WHY THIS IS HAPPENING: your fingertips aren't flat so the back will not be either. SOLUTION: if you want a perfectly flat back place a piece of glass over the filled mold and press until you can see that it is flat. You may have to trim any "overspread" with a craft knife. Note - if you place a stiff piece of clear release sheet under our special acrylic square tileyou can pull it out easier. Find our Starter Tool Kit here.Please read our complete instructions to learn more about this technique.