Thermal paper rolls feature three layers, although you will not notice them from the look. The first layer is the substrate layer, which is just the paper. Then, the base layer acts as the binding element and allows the transfer of heat through the paper.
Finally, the active layer contains specially formulated chemicals, allowing the ATM paper rolls to react to heat.
High-quality thermal printer rolls feature an additional protective layer, which helps to prevent the printed surface from fading.