🔗 Letterlocking (Wikipedia)

Letterlocking is the act of folding and securing a written message which could be on papyrus, parchment, or paper, so that it does not require an envelope or additional enclosure. It is a document security tradition which utilizes folding and cutting. The process dates to the 13th century in Western history, corresponding with the availability of flexible writing paper. Letterlocking uses small slits, tab, and holes placed directly into a letter, which combined with folding techniques are used to secure the letter ("letterpacket"), preventing reading the letter without breaking seals or slips, providing a means of tamper resistance. These folds and holes may be additionally secured with string and sealing wax. A Scottish diplomat in Italy, William Keith of Delny, sent letters to James VI of Scotland which would tear in two if not opened with care.

Intricate letterlocking works contain artistic elements, demonstrating more than a utilitarian purpose. While the use of sealing techniques may have been limited to ecclesiastic and the nobility, letterlocking was historically performed by all classes of writers. An individual could also be recognised by their personal technique of folding, as was the case with Jane Whorwood, of whose letter Charles I, imprisoned in Carisbrooke Castle on the Isle of Wight, wrote: "This Note [...] I know, by the fowldings [...] that it is written by [Mrs Whorwood]".

Letterlocking is also a discipline focusing on "the materially engineered security and privacy of letters, both as a technology and a historically evolving tradition."