Thermal relief printing
Thermographic printing (also Thermography or thermal printing) is a finishing process for printed matter, the writing and drawing in relief lifts off the paper. The technology came to Europe from the USA in the late 1970s.
history
The print-finishing process thermographic printing to the expensive and complex historical steel engraving or embossing replace at favorable prices. The result of both processes is a lettering or drawing that is raised on the printing medium (paper) and that is slightly curved and stands out from the background like a relief. The most common uses are higher quality business cards or letterheads.
While this result is achieved with classic steel engraving by engraving the drawing or the letters reversed into a metal plate and then printing in gravure , whereby the bulge is created by strong (physical) pressure, thermal relief printing uses a chemical route by heating a plastic granulate.
technology
The fresh print, preferably produced by offset printing , but also by screen printing or letterpress printing, is sprinkled with plastic granules that combine with the respective, still wet printing ink , but can be sucked off the bare paper base. You can also add pearlescent pigments to the granulate. In a subsequent heat treatment in an infrared heater, the colorless powder melts with the damp printing ink, swells, dries and then forms the desired relief-like, approx. 0.2 mm high elevation, which is perceived visually and haptically as "complex, elegant" .
Fine granules are used for thin lines and small letters , and granules with a coarser grain for surfaces and larger picture elements, the grain size corresponding to the thickness of the relief. However, the thermal relief process does not achieve the image sharpness of the steel engraving. It is essential that only full tones are suitable for thermal relief printing , half-tone images or 4- color prints cannot be produced technically. Multi-colored thermal relief prints are possible; if the colors are adjacent, care should be taken to overprint them to avoid "flashes". The maximum print format is limited to A4 (in exceptional cases, A3 ). Smooth, non-absorbent papers from 90 g / m² are suitable as print media.
literature
- Gavin Ambrose, Paul Harris: Basic knowledge of production for graphic designers: A handbook for graphic designers , Stiebner Verlag, 2008, ISBN 978-3-83071356-2 , pp. 170, 171
- Franziska Morlok, Till Beckmann: Enzyklopädie der experimental Druckveredlung , De Gruyter, Munich, 2013 ISBN 978-3-03460901-2 , p. 24
Web links
- Relief printing (thermography) . In: printperfection.de