You can go without the teflon sheet in between, just be sure to flip the shirt inside out right after you apply the heat otherwise they will stick together. We always use a teflon sheet over the numbers and covering any imprint. If you get the imprint with the heat press it will stick to the bottom of the heating element, possibly mess it up and it will transfer to the next thing you put in the press. Follow the directions for the vinyl numbers too much pressure, heat or time they will get stiff, too little they will peal off and not necessarily now but later down the road after they have been washed a few times.
