Thermal paper

Thermal paper is a special type of paper that, when in contact with heat, changes its colour to black or, sometimes, to blue or red. The terms ‘heat-sensitive paper’ and ‘audit roll’ are often used as synonyms for thermal paper.

Thermal paper is mainly used for thermal printing.

The most common applications are cash registers and ATMs, which incorporate a small thermal printer used to print receipts. The paper used to print such receipts is thermal paper.

In addition to cash registers and ATMs, thermal paper is used to print labels. Labels printed with thermal paper and often called thermal labels. Printing labels with thermal paper has become a widely used option because of the advantages thermal printing has (e.g. low cost, high quality printing).

The structure of thermal paper varies depending on several factors, including the durability of the printed design.

Usually, thermal paper is made of four different layers:

• The substrate, which consists of paper.
• The base coat, which allows the heat to move through the thermal paper.
• The active coat, used to improve uniformity and heat insulation.
• The thermal layer, which makes the paper change colour when in contact with heat. The chemicals that cause the paper to react to the heat are contained in this layer.

Compared to normal paper, thermal paper has several advantages, including the following:

• High quality and accuracy: thermal paper allows for high accuracy and quality printing.
• Low costs: printing over thermal paper does not require ink, only heat. As a result, the costs of buying and maintaining ink cartridges are saved.
• Fast printing: with thermal paper, printing happens in a much faster way than with normal paper since thermal printing heads have the capacity to generate designs in milliseconds.
• Low maintenance: since ink is not required to print over thermal paper, the maintenance of a complex ink-based printer is not necessary.

As already mentioned, thermal paper is used to print labels that are often called thermal labels. In order to do this, a thermal printer is used. More specifically, the head of the thermal printer processes the design that must be printed and heats the thermal paper, changing its colour. The result of this process is a design printed over the paper. No inks are used, which means ink-based printers like inkjet printers or traditional label printers are not necessary.

Thermal printers are not limited to simple designs (e.g. text), but can also print more elaborate elements such as barcodes.