Letterlocking – Unlocking History

Welcome to letterlocking! You can find essential information about letterlocking and the Unlocking History research team on this page. Please be reminded that this is work-in-progress. We will be updating the website regularly, including major uploads to the Dictionary of Letterlocking (DoLL) – so please check in periodically, and follow us on social media for all the news @letterlocking.


Unlocking History

Unlocking History is the name for a group of conservators, paleographers, literary scholars, publishers, book-artists, imaging experts, engineers, and scientists who are interested in the historical practice of letterlocking. We want to make sure letters are conserved properly so that they can be studied for the verifiable secrets they reveal. The material features of letters can speak to us about the past, but in order to hear them we have to learn their language. The Unlocking History team is dedicated to bringing together all the tools we need to do so – a dictionary, instructional videos, images, and hands-on workshops in libraries, museums, universities, and schools around the world.

Letterlocking and the Dictionary of Letterlocking (DoLL)

Letterlocking refers to the technology of folding and securing an epistolary writing substrate to function as its own envelope – a vital communications technology before the invention of the mass-produced envelope in the 19th century. A full definition of letterlocking can be found in the Dictionary of Letterlocking (DoLL).

Documenting the physical details of well-preserved letters has helped us discern and define different locking categories with multiple levels of built-in security and various authentication enhancements. DoLL will explain the key differences between these categories – and show you how to model them. With practice, you will be able to examine flattened historical letters in libraries and archives, and make models to discover which letterlocking category the writer or secretary was using. These categories may correlate to the sensitivity of the information contained inside or contribute to the meaning of the text they carry.

Imaging and Conservation

The study of letterlocking is important for the preservation of documents because it informs conservators about the evidential value of creases, slits, and holes and other manipulations.  #PreserveTheFolds.


Letter writing materials tools and techniques

The study of letterlocking encompasses research into the materials, tools, and techniques of writing. Studying the material aspects of letter-writing – the quality of paper, for example, or the specific way wax was applied – offers researchers a chance to gain a richer understanding of past means of communication, allowing them to explore what is expressed by a document beyond its written text. Unlocking History members have spent time trying to replicate the conditions of early modern letter-writing – making ink and wax according to early recipes, working with handmade paper, and attempting to break into locked letters undetected, as if we were seventeenth-century spies. We also study the ways in which developments in communication technologies interact with language, literature, and culture throughout history (for example, when we talk about giving someone "the seal of approval").


This video short introduces the emerging field of letterlocking while offering a glimpse into a day of shooting instructional videos. Produced, directed, and edited by Vincent Thuet, Freelance Editor and Videographer. Funded by the Gladys Krieble Delmas Foundation and the Massachusetts Institute of Technology (MIT) Libraries.