Watermark
A paper security feature which is visible in transmitted light as an image appeared due to local differences in paper density. A watermark is formed on a wet paper web in the process of paper production. It is formed by the density of fibres on certain areas of an image. Darker areas contain more fibers. Lighter areas contain a smaller amount of fibers. Watermarks differ by several criteria.
By location:
- General — an image repeated at regular intervals all over a document page.
- Local — an image located in a certain place of a document page.
By general paper tone:
- Single-tone — consists of dark or light elements of an image compared to a general paper tone.
- Duotone — consists of dark and light elements of an image compared to a general paper tone.
- Multitone — consists of dark and light elements of an image compared to a general paper tone which are gradually transforming into each other.
Fig. 1. New Zealand. Travel document (Convention of 28 July 1951) issued in 2016. General duotone watermark
Fig. 2. Great Britain. Passport issued in 2016. Local multitone watermark
Fig. 3. Ukraine. Refugee's document for travelling abroad issued in 2017. General single-tone watermark
Fig. 4. Belarus. Diplomatic passport issued in 2010.General duotone watermark
Fig. 5. France. Diplomatic passport issued in 2008. General multitone watermark
Fig. 6. Estonia. Travel document (Convention of 28 July 1951) issued in 2013. Local multitone watermark and CORNERSTONE watermark with dark lines in the corners of the document page which prevents bent corners (marked with an arrow)