Letterlocking

Letterlocking is the act of folding and securing a written message (such as a letter) on papyrus, parchment, or paper, without requiring it to be contained in an envelope or packet.

[4] A particularly intricate method known as a spiral lock was in use by people of many social backgrounds in early modern Europe, including monarchs Mary Queen of Scots and Elizabeth I of England.

[6] In 1603 King James told the Venetian diplomat Giovanni Carlo Scaramelli, with a smile, that he had previously received letters from the Doge of Venice which he could not open without breaking the seal.

[12] The Envelope and Letter Folds Association (ELFA) is an informal organization of enthusiasts founded in 1988-89 and which at one time had local groups in the Netherlands, Belgium, and Germany.

[15] The digitally unfolded letter, sealed since 1697 and secured by eight folds, had been previously scanned using X-ray microtomography (XMT), a technology used in dental and other medical, industrial, and archeological research.