Thermal paper is a specific form of paper that consists of two distinctly different sides. One side is chemically treated specially to change in the presence of heat, which is where the name ‘thermal’ comes from. The side which is chemically treated is easily recognisable because it is ‘shiny’ to look at and marks very easily, for example when scored with a fingernail. This is the side which is printed on when used in a thermal printer. The electrically heated pins that impress an image onto the paper press themselves onto this side. As they are heated, the heat sensitive chemical reacts and becomes a black colour. The pins impress the image necessary and the dots turn to black, showing the image clearer. In this way, you are able to print text and basic images on to the paper.
Because of this unique method of printing, it is not necessary for any ink to be involved at all in the process, as the text comes from the combination of the heated pins and the heat reactive chemical. Therefore, there is no need for an ink ribbon to be installed and used in a thermal printer, saving time and money.
Thermal paper is most commonly used in machines that need a simple product such as the receipt in a till. Some tills do NOT use thermal paper, therefore need an ink ribbon to accompany their paper. The advantage here is that the printer is able to print in many colours, not just monochromatic black colour found with thermal paper. However, some tills that only need simple receipts, such as the Casio TE-3000, use thermal paper and printers as they produce quick, low-resolution print.
Thermal paper also played a big part in the development of the fax machine. In the 1980s when the fax machine was first developed the majority of the machines used thermal paper, but as the faxes became more detailed a different form of paper was necessary. In more modern times, thermal paper’s main uses include receipts, calculator paper and recording data in medical centres.