Filigranology is the study of

watermarks A watermark is an identifying image or pattern in paper that appears as various shades of lightness/darkness when viewed by transmitted light (or when viewed by reflected light, atop a dark background), caused by thickness or density variations i ...

. It is usually pursued in order to discover information about the date and origin for a paper-based piece of writing or a piece of art. There are several catalogues of watermarks – most notably C. M. Briquet's, ''Les Filigranes'' (1907) – including illustrations of many watermarks from dated documents to aid those wishing to undertake this kind of research.Bidwell, J. (1992). The study of paper as evidence, artefact, and commodity. pp 69-82. in Davison, P. H. ''The Book encompassed: Studies in twentieth-century bibliography''. Oak Knoll Press
(Accessed in Dec 2013)

References

{{Reflist Watermarking Papermaking Paper