Letterpress Printing
A printing technique when ink is applied to a substrate from a printing plate with printing elements raised above spacing elements. During printing spacing elements do not touch the print-receiving material. The process is carried out under high pressure (at least 15 kg/cm2) with the use of fast-drying inks.
Special features of the print:
- uneven ink distribution in strokes: less ink in the middle than along the edges;
- a rim formed by the ink along the edges of a stroke;
- deformation of the print-receiving material: protuberance on the back side of a sheet and indentation on the front side of a sheet in the area where the print is applied.
Letterpress printing is often used for printing serial numbers, barcodes, and design elements of covers.
a
b
c
d
Fig. 1. Qatar. Travel document issued in 2005:
a — page 32. Paper substrate; b — the same. Serial number. Front side of the print. Letterpress. Uneven ink distribution in strokes. White light; c — the same. Substrate deformation: protuberance on the back side of a sheet caused by the pressure of the printing plate. Oblique light; d — the same. Zoomed fragment. A rim along the edge of the stroke (marked with arrows)
a
b
c
Fig. 2. China. Passport issued in 2013:
a — data page. Paper substrate; b — the same. Serial number. Two inks applied while using the Orlov printing method. Letterpress. White light; c — the same. UV light