How can you tell if paper is thermal paper?

It’s the easiest way to identify if it is thermal paper. To ensure you have the right thermal paper, conduct a scratch test on both sides and see if you can see the black marks. If, after scratching, you don’t see any black dots or markets on either side, then it is not thermal paper.
Thermal paper is a special coated processed paper with an appearance similar to that of ordinary white paper. The thermal paper has a smooth surface and is coated with a thermal coating, both on the surface of ordinary paper, using ordinary paper as the paper base. The color-emitting layer consists of binder, color developer, and colorless dye (or hidden color dye), which is not separated by microcapsules and the chemical reaction is in latent state. When the thermal paper sheet touches the thermal print head, it reacts chemically with the color developer and the colorless dye.