underprints

Underprints are secondary images, text, or patterns printed on a substrate beneath the visible surface of a printed item, such as paper used for stamps, banknotes, certificates, or other security documents. They are typically applied during the production process or by a secondary printing pass and are designed to be difficult to reproduce, providing an additional layer of security, authentication, or aesthetic depth.

In security printing and philately, underprints often take the form of faint inscriptions, logos, numerals, or geometric motifs that lie beneath the main design. They may be created to deter counterfeiting, indicate the issuing authority, or convey additional information about the issue. Underprints can be designed to be detectable only under special conditions, such as oblique lighting or ultraviolet illumination, making unauthorized production more challenging.

Production methods for underprints vary. They can be incorporated into the paper itself during pulping or sheet fabrication, or added as a separate printing operation on the reverse side or beneath the top layer of ink. Common techniques include intaglio, lithography, offset printing, and screen printing, depending on the required level of sophistication and the printing workflow.

The presence of an underprint can affect the value and handling of a collectible item. For collectors, underprints are documented as varieties or security features and can help verify authenticity or indicate a specific issue. Variations in placement, content, or visibility of underprints may create distinct catalog entries and influence condition assessments.

See also: watermarks, security features, overprint, anti-counterfeiting measures.