Thermographic Printing
Thermographic printing (raised printing) is a post print technology of producing a tactile raised print. The printed area is dusted while wet with low-melting polymer powder which sticks to the ink. The excess powder is removed from non-printed areas by shaking off or blowing off. Then the substrate is heated, and, as a result, the powder melts and forms a raised relief on the substrate. The powder that is used in thermographic printing can be transparent, glossy or matte.
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Fig. 1. Moldova. Emergency travel document issued in 2013:
a — single sheet document. Front side. Paper substrate; b — the same. Zoomed fragment. Thermographic printing. Raised relief is formed by transparent melted polymer powder. Glossy prints
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Fig. 2. Moldova. Visa:
a — paper substrate; b — the same. Zoomed fragment. Thermographic printing. Raised relief is formed by transparent melted polymer powder with a yellowish tint (marked with arrows); c — the same. Zoomed fragment. Thermographic printing. Glossy melted polymer powder extends beyond the edges of letters (marked with an arrow). View at an acute angle of observation