Watermark
Definition
A pattern formed in paper during manufacture by localised fibre-density variation on the Fourdrinier wire; visible in transmitted light as a lighter (thinner) design; impossible to add to finished paper without destruction, and therefore serves as both an authentication feature and a page-substitution indicator.
- Formation method
- Fibre-density variation impressed during paper manufacture on a Fourdrinier wire
- Detection method
- Transmitted light (holding the document up to light)
- Forensic value
- Cannot be added to finished paper; used for authentication and tampering detection
- Common uses
- Currency, stamp paper, and security documents
Common questions
How do you spot a watermark on a document?+
Hold the document up to light (transmitted light) to see the watermark as a translucent design. It appears lighter or darker than the surrounding paper because it's a variation in paper thickness or fibre density, created during manufacture. You cannot see it reliably in ordinary reflected light.
Why do forensic examiners care about watermarks?+
Watermarks are built into the paper during manufacturing, so they cannot be added to a finished document. This makes them powerful for two things: proving the paper is authentic (matching the design to manufacturer records) and detecting page substitution or alteration. If a watermark is missing or doesn't match the expected date of manufacture, the document may be forged or tampered with.
Where do you find watermarks on real documents?+
Watermarks are a standard security feature on currency, stamp paper, and security documents like bonds or official seals. For example, Indian currency notes display the Mahatma Gandhi portrait watermark along with the denomination numeral.
Related terms
- Optical Brightening Agent (OBA)
- A fluorescent compound added to paper pulp or coatings that absorbs UV-A radiation and re-emits it as visible blue light, making paper...
- Aging Index (Aginsky)
- The ratio of phenoxyethanol concentration in an unheated (cold) extract to its concentration in a heated extract from the same ink stroke;...
- Aginsky Method
- Solvent-extraction ink-age dating (Valery Aginsky, 1996). Compares fast and slow solvent extractions of phenoxyethanol to derive an aging parameter for ink under...
- ASTM E2494
- ASTM International's Standard Guide for Using Ink Examination Methods in Questioned Document Investigations; sets out the recommended tiered analytical approach, uncertainty reporting...
- ASTM E2789-11
- ASTM standard guide for forensic examination of inks (ink-age dating context). Pairs with ASTM E1422 for paper examination by FTIR.
- Ballpoint Ink
- An oil-based, high-viscosity ink using a resin binder (alkyd or polyamide) in a high-boiling solvent (phenoxyethanol or benzyl alcohol), with triphenylmethane dyes...
- Banding
- Horizontal density variations across a laser or inkjet printed page, arising from developer roller irregularities, drum charging variation, or drive-train gear-skip; measurable...
- Brunelle R-Ratio Method
- Dye-degradation method (Richard Brunelle and Kenneth Pro, 1972, later refined). Tracks the ratio of extracted and unextracted dye over time to estimate...
- Daisy Wheel
- A circular print element with flexible plastic spokes each bearing a character, used in electronic daisy-wheel typewriters and printers from the late...
- Document
- Any matter expressed or described upon any substance by means of letters, figures or marks intended to be used for the purpose...
- Dye-Based Ink
- Soluble colourant dissolved in solvent. Modern fountain-pen and dye-based ballpoint inks belong here. TLC separates the dye mixture into resolvable spots.
- Dye-Decay Dating (LaPorte Method)
- An ink dating method that uses HPLC-PDA to monitor the relative concentrations of specific dye components and their degradation products; the ratio...
Explained in these topics
- Detection Methods: Oblique, Transmitted, UV, IR and the VSCA pattern formed in paper during manufacture by localised fibre-density variation on the Fourdrinier wire; visible in transmitted light as a lighter (thinner)...
- Documents: Definition, Types and Preliminary ExaminationTranslucent design impressed into paper during manufacture, visible by transmitted light. A primary security feature of currency, stamp paper and security docu...
- Ink Dating and Paper Examination: Fibres, Watermarks, BrightenersA translucent design element formed during paper manufacture by a thinner paper layer at the design location; visible under transmitted light; its design can b...
- Inks, Papers and Age of DocumentsVariation in paper thickness or fibre density introduced during manufacture, visible as a lighter or darker image under transmitted light. Used in currency, st...
- Typescripts, Printed Matter, Currency and Mechanical ImpressionsImage formed by varying paper thickness during manufacture, visible against light. MGNS notes carry the Mahatma Gandhi portrait watermark plus an electrotype o...