Stamp printing sits at the intersection of commercial reproduction and security printing — the image must be beautiful, and the result must be difficult to counterfeit. Five methods have been used in Chinese stamp production, each producing a distinctive visual fingerprint that philatelists and security printers both recognize.
Offset Lithography
Image and non-image areas share the same plane, separated by chemistry — the image accepts ink, the background accepts water. The inked image transfers first to a rubber blanket, then to paper. The dot structure is the same as commercial offset: variable dot size at a fixed screen ruling. Fine for color reproduction, but the flat ink film offers no tactile relief and limited security. Imprint edges are clean — no squeeze-out characteristic.
Letterpress
The inverse of gravure: raised image areas transfer ink; recessed areas stay clean. Dots vary in size like offset, but the heavier impression pressure characteristic of letterpress forces ink to the perimeter of each printed element. Under magnification, letterpress-printed stamps show a telltale darker rim around every dot and character — ink squeeze-out at the edge of the raised surface. Text and backgrounds typically print solid without screening.
Photogravure (Heliogravure)
The dominant stamp printing method worldwide. Unlike offset and letterpress — where tone is controlled by dot size at fixed spacing — photogravure uses fixed-size cells at variable depth. Deeper cells hold more ink and print darker; shallower cells print lighter. The result: continuous-tone reproduction with rich color saturation and fine detail that neither offset nor letterpress can match. Under magnification, the cell structure is clearly distinct from the variable-dot pattern of offset.
The liabilities: deep shadow areas can show irregular flow marks (gravure’s characteristic solvent-related mottle), and fine text or thin lines break into a sawtooth pattern because they’re composed of discrete cells rather than continuous strokes.
Hand-Engraved Intaglio
The artist cuts directly into a steel plate, building tone through line density and depth rather than dots. Printed under extreme pressure, the ink transfers from the recessed lines to form raised ridges on the paper surface — run a fingertip across an engraved stamp and you feel the relief. Under magnification, each line shows the tool mark of the engraver’s burin. This combination of tactile relief and hand-executed line work makes engraved intaglio the most counterfeit-resistant printing method in existence. It’s the foundation of banknote printing for the same reason.
Engraving + Photogravure Hybrid
Engraving can’t reproduce continuous-tone color. Photogravure can’t produce sharp, unbroken lines or genuine tactile relief. Combining the two: photogravure carries the color, the tonal gradation, and the broad image areas; engraving overlays the crisp line work, the fine text, and the anti-counterfeiting structure. Each method compensates for the other’s weaknesses. The result is a stamp with photogravure’s color depth behind engraving’s security — the standard for premium commemorative issues.
References
- Wikipedia: Offset Lithography: Comprehensive overview of offset printing including plate chemistry, blanket transfer, and dot structure relevant to stamp production.
- Wikipedia: Letterpress Printing: Relief printing technology including type-high surfaces, impression mechanics, and the characteristic ink-squeeze edge effect.
- Wikipedia: Photogravure (Rotogravure): Gravure printing including variable-depth cell structure, continuous-tone reproduction, and the cell pattern visible under magnification.
- Wikipedia: Intaglio Printing: Hand-engraved and etched intaglio techniques including plate cutting, ink transfer under pressure, and the raised-line tactile security feature.
- Wikipedia: Security Printing: Anti-counterfeiting print technologies including intaglio relief, microtext, and hybrid process combinations used in stamps and currency.