Thermal printing

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History of printing
Techniques Woodblock printing 200 Movable type 1040 Intaglio (printmaking) 1430 Printing press c. 1440 Etching c. 1515 Mezzotint 1642 Relief printing 1690 Aquatint 1772 Lithography 1796 Chromolithography 1837 Rotary press 1843 Hectograph 1860 Offset printing 1875 Hot metal typesetting 1884 Mimeograph 1885 Daisy wheel printing 1889 Photostat and rectigraph 1907 Screen printing 1911 Spirit duplicator 1923 Dot matrix printing 1925 Xerography 1938 Spark printing 1940 Phototypesetting 1949 Inkjet printing 1950 Dye-sublimation 1957 Laser printing 1969 Thermal printing c. 1972 Solid ink printing 1972 Thermal-transfer printing 1981 3D printing 1986 Digital printing 1991
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Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated elements. The coating turns black in the areas where it is heated, producing an image.^[2]

Most thermal printers are monochrome (black and white) although some two-color designs exist. Grayscale is usually rasterized because it can only be adjusted by temperature control.^[3]

Thermal-transfer printing is a different method, using plain paper with a heat-sensitive ribbon instead of heat-sensitive paper, but using similar print heads. Thermal transfer printer require the use of wax-based ribbons that adhere to the substrate during the printing process.^[4][5] As a result, users must load both labels and ribbon, essentially using an alternative ink system.^[6]