3 inch label roll

A thermal printer typically contains at least these components:

• Thermal head: Produces heat to create an image on the paper
• Platen: A rubber roller which moves the paper
• Spring: Applies pressure to hold the paper and printhead together

Thermal paper is impregnated with a solid-state mixture of a dye and a suitable matrix, for example, a fluoran leuco dye and an octadecylphosphonic acid.

This process is usually monochrome, but some two-color designs exist, which can print both black and an additional color (often red) by applying heat at two different temperatures