»ÆÉ«²Ö¿â

Letterlocking is the art of folding and securing a letter so that it functions as its own envelope. In the Western world the practice spanned the thirteenth to the nineteenth centuries, following the increasing availability of flexible, foldable paper, and pre-dating the mass-produced envelope. It utilises a combination of folds, tucks, slits, threads and wax seals to tamper-proof the letter and ensure privacy.

While perusing our collection, I discovered interesting examples of different types of letter packets and the personal folding styles of individual correspondents. With no prior knowledge of this practice, I was keen to investigate further. A recently published book on the topic, , by Jana Dambroglio and Daniel Starza Smith with the , was invaluable in helping me identify crease patterns and the different manifestations of letterlocking within this series.

Letterlocking categories and formats chart, demonstrating various manipulations, from Letterlocking: the hidden history of the letter

It appears our letters follow the fashions of the seventeenth century. Below is a selection of examples that illustrate distinct letterlocking styles, including tuck and seal, flossing, and wrapping. The Early Letters I am focusing on are flattened and bound in a volume, but the placement of folds reveals the methods used at the time of creation.

The most common letterlocking method in personal correspondence, ‘tuck and seal’, involves folding the top and bottom thirds of the letter over one another, obscuring the text, to form an oblong. The oblong is then folded again so that one end is tucked into the other and finally sealed with wax.

(top) , an example of a tuck and sealed letter; (bottom) , an example of a visible open edge

Another interesting variation of push and seal is the ‘pushed-in fold’ technique. This involves creating new creases in the paper, typically at a 45-degree angle, by pushing an existing mountain fold inward. This 1737 letter from Gasparo Cerati () illustrates the mechanisms of the pushed-in fold:

The dirt pattern along the creases of this 1673 letter by Jean Baptiste Du Hamel () reveals how the paper was manipulated into a letterpacket:

It struck me that conservators are routinely requested to clean off this type of dirt, thus removing integral material evidence. It has inspired me to reconsider how I might approach the preservation of such letters in future.

A more intimate and secured letterpacket intrigued me the most: the flossed letter. Typically associated with the most private communications, a flossed letter is secured by wrapping a strong thread, typically silk floss, around a small, narrowly-folded letter packet, topped with a wax seal. Its diminutive size enables both sender and recipient to hold the letter in their palms, to slip it into a pocket, or discreetly hide it up a sleeve, conjuring images of clandestine note-passing in plain sight. Daniel Starza Smith identifies that ‘letter-flossing seems to have entered England around 1579, in letters to Elizabeth I from France and Scotland’, and explains that while the practice is commonly associated with the aristocracy, it was also a method used by other types of correspondent to embed ‘meaningful social signals’ by strengthening the rhetorical impact of the letter.

This is demonstrated in our example below, , written in 1668 by Pierre de Carcavi (1600-1684), French mathematician and secretary of the National Library of France under Louis XIV, to Royal Society secretary , stressing the importance of good communication between the English and French natural philosophical societies. Sending this type of diplomatic message by taking the effort to present the letter as a meaningful, intimate gift, complete with trimmings and finery, signals the high esteem in which the author holds the recipient. The faint remnants of the accordion folds, the typical use of two wax seals, and a colourful ribbon befitting the author, can all be seen here:

Some letters were enclosed in a custom wrapper, being a container made of paper fashioned to fit around and house the letter contents, which could include letters, enclosures, botanical specimens and so on. These were then addressed and fastened securely for delivery. This beautiful example of a wrapper containing meteorological observations was sent by Giovanni Poleni from Padova, Italy, in 1737 ():

I now realise that, prior to learning about letterlocking, I didn’t appreciate the art of letter writing in its entirety. Rather than focusing on the informational value contained in the text, I now recognise the extent of overlooked features which help us understand records in more depth. Thinking about manuscript letters as three-dimensional, dynamic objects, crafted creatively and with purpose, and peppered with marks of personality, results in a more thorough and all-encompassing approach to cataloguing them.

Similarly, this perspective will go a long way in assisting me with the future conservation of letters, bearing in mind the ease with which the pursuit of restoring the document can cover up integral material evidence. I look forward to applying this new knowledge during my next cataloguing project.

Much more can be said on this fascinating topic. For those interested in pursuing it further, I recommend the following resources:

• Dambroglio, Jana and Smith, Daniel Starza (MIT Press, 2025)
• The
• : the complete correspondence, 1550-1608