Thermal paper is a special type of paper for the thermal printing process and has a special coating. On the print side, thermal paper contains colour formers and colour developers. The heat is transferred by thermal stamp, thermal nib or laser beam and thus the writing becomes visible by melting the temperature-intensive dyes.

What is thermal paper made of?

Thermal paper is largely made up of three layers: The base paper is relatively thin (41.5 g/m2 for comparison - normal paper weighs 80 g/m2); the Z-layer and the thermal layer together weigh about 11.5 g/m2.   The user can choose between 3 font colours, but black is clearly the most popular. Different printing temperatures achieve several colour levels on suitable thermal paper in special printers.

The thickness of the paper is crucial for durability. Thicker paper has a higher tolerance to mechanical stress. For receipt printing, the standard paper weight is 48 to 55 g/m², whereas for tickets and lottery tickets, more stable paper qualities are used.  There is thermal paper that fades badly after a very short time, but there is also paper with a 25-year durability guarantee. 

However, printing on thermal paper is generally not considered document-proof. Therefore, for documents that need to be kept for years, copies should be printed on plain paper. Thermal paper fades when exposed to direct sunlight and heat. The industry is working at full speed on further development and has already had some successes, especially great progress has been made in the storability of printed thermal paper.