Thermal printer
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Direct thermal printers create an image by selectively heating coated paper when the paper passes over the thermal print head. The coating turns black in the areas where it is heated, creating the image. More recently, two-color direct thermal printers have been produced, which allow printing of both red (or another color) and black by heating to different temperatures.
Direct thermal printers are increasingly replacing the dot matrix printer for printing cash register receipts, both because of the higher print speed and substantially quieter operation. In addition, direct thermal printing offers the advantage of having only one consumable - the paper itself. Thus, the technology is well-suited to unattended applications like gas pumps, information kiosks, and the like.
Until about 2000, most fax machines used direct thermal printing, though, now, only the cheapest models use it, the rest having switched to either thermal wax transfer, laser, or ink jet printing to allow plain-paper printouts. Historically, direct thermal paper has suffered from such limitations as sensitivity to heat, abrasion (the coating can be fragile), friction (which can cause heat, thus darkening the paper), light (causing it to fade), and water. However, more modern thermal coating formulations have resulted in exceptional image stability, with text remaining legible for an estimated 50+ years.