Letterlocking: Catherine de’ Medici’s concealed spiral-locked letter to Raimond de Beccarie ()

Modelled after Catherine de’ Medici’s signed holograph letter to Raimond de Beccarie, Monsieur de Fourquevaux (), MIT Libraries’ Department of Distinctive Collections, C38 1570. This letter, modeled after a spiral-locked letter by Queen Consort of France, Catherine de’ Medici, features a sword-shaped lock sliced out of the left margin. After a series of roll folds - all carried out with the lock left protruding - the resulting long strip is folded in half short edge to short edge to form the letterpacket. One slit is made using a bradawl, allowing the pinched lock tip to pass through all layers of the substrate. Two more slits are made, through both the packet and lock, and the lock tip passes through all layers of the letter substrate, and itself, twice, in a spiral motion. Once the lock has been threaded in this way, the packet is very difficult to break into undetected. The recipient literally has to tear the lock in four locations before they can open the letter to read it. Sealing wa