Thermal paper serves various functions: it acts as a medium for transmitting text and graphics in fax machines (fax paper); serves as a recording material in medical and measurement systems (such as ECG charts and thermal instrument recording paper); is used as printing paper for internet terminals; and is utilized in commercial applications for labels, POS receipts, and the like-with fax paper accounting for the largest share of usage.
The production principle involves coating a standard paper base with fine particles-specifically colorless dyes and phenolic compounds or other acidic substances-separated by a thin film; when exposed to heat, the film melts, allowing the powders to mix and trigger a color-forming reaction. Images or text produced on thermal paper are unstable and prone to fading, which can make the content difficult to read.
Common lottery tickets are made of thermal paper.
While standard thermal paper is unsuitable for long-term storage, high-quality thermal paper can now be preserved for 30 years or even longer.