Thermal paper is coated with a chemical that changes color when heat is applied. This means that when a thermal printer applies heat to the paper, it creates the image or text on the paper. However, the chemical used in thermal paper is not very stable and degrades over time, causing the text or image to fade.
Additionally, thermal paper is sensitive to heat, light, and humidity. Exposure to any of these elements can cause the paper to yellow, fade, or become brittle, which can make it difficult to read the printout. This sensitivity makes thermal paper receipts unsuitable for long-term storage.
Moreover, the chemical used in the thermal paper can also be harmful to the environment. Thermal paper receipts often contain bisphenol A (BPA), a chemical that has been linked to health problems. As a result, many countries have banned the use of BPA in thermal paper, which can further compromise its durability.
In conclusion, thermal paper receipts are not suitable for long-term storage due to the chemical instability and sensitivity of the paper. It is best to keep a digital copy or print the receipt on more durable paper if you need to keep it for a long time.