Recchōsō, sometimes spelt Retchōsō, or Tetchōsō, is the Japanese term for a multi-section binding.
For a long time, the recchōsō binding structure was believed to only be used in Japan. However, examples of similar bindings were discovered in the Caves of Dunhuang  making it an early Chinese binding technique that was presumably developed in Japan over time, like most other Japanese bookbinding techniques. This structure is found in Japan as early as the late Heian period (794-1185).
Although it is not entirely clear how and when the multi-quire book developed in China, it was not widely adopted. Its lack of uptake may be linked with the rise of woodblock printing and the broader adoption of the “butterfly” binding structure (decchōsō or kochōsō in Japanese) as the preferred codex format for printing. This binding, which consists of folded bifolia joined to each other with paste at the spine so that each pair of leaves opens at an angle like the wings of a butterfly, was preferred for printed material in China. 
The recchōsō binding and other multi-quire bindings in Japan and China are often linked with manuscript material. That is the action of writing by hand, whether for documentary records, account books (hantori chō) or works of literature.
In Japan, a refined recchōsō binding, using silk covers and good quality paper, became popular in the Edo period (c.1603-1868), as one of the main book formats for handwritten poetry, Nō chants and beautifully painted works such as the illustrated narrative books sometimes known as Nara ehon.
This traditional binding technique is different in many ways from other Japanese bindings. Its construction allows the sewn book to open flat. Other methods such as traditional stab bindings or “butterfly” bindings do not allow for such a flat opening without putting some pressure on the structure while manipulating the book.
The recchōsō binding structure has, at first sight, more in common with a Western multi-quire book than other Japanese bindings, but the sewing method and cover attachment are very different so no further comparisons can be made.
The covering material (soft cloth, or paper in the older binding examples) is hooked around the first and last quire of the textblock and tipped into place. The book-cover is then built around the first folio.
The first and last quires are then sewn with the remaining textblock. Each quire is slit at the spine with a small knife to mark the sewing stations and the textblock is sewn at four stations, using four needles to create two pairs. In some variations, only one needle is used with the traditionally red silk thread.
The sewing is unsupported, with no links between each of the quires as the thread passes through the textblock. The absence of a link requires constant and even tension on the sewing thread to maintain a tight opening. At the end of the sewing, each pair of sewing threads are knotted individually inside the last quire. The threads are then tied together in the centre of the gathering, creating a neat bundle of thread in the spinefold. Several different knotting techniques can be observed.
The soft covers are reinforced with the addition of a “doublure” made of decorative paper, often gold, adhered at the edges on the cover turn-ins only. The binding is now finished as there are no endbands and no further spine treatment. In his book on Japanese bookbinding, Kōjirō Ikegami describes a detailed step-by-step instruction to make a model of this historical binding .
Traditionally, this binding could be made with a minimum of two quires, but the number of quires could vary in size to accommodate more text, up to a maximum of five or six quires. These bindings are often found as part of large volume sets kept together in wooden or lacquer boxes.
These structures have several conservation issues including breakage of the sewing thread, which can lead to loss of integrity of the binding structure and possible loss of content; damage to the delicate textile fabrics; and lifting and creasing of the doublures and covers.
The recchōsō structure is an intriguing early Chinese and Japanese bookbinding structure. Its evolution over time is a fascinating subject which deserves further research.
Julia Poirier, Book and Paper Conservator
Edo in Colour: Prints from Japan’s Metropolis is open now at the Chester Beatty. We do hope you’ll be able to visit!
Inspired by the seasonality of these artworks, this exhibition will be shown in two parts: Part 1: 28 May – 29 August 2021; Part 2: 4 September – 5 December 2021. The exhibition will close for changeover from 30 August to 3 September.
 For more information on the International Dunhuang Project and the recchōsō structure, see: http://idp.bl.uk/education/bookbinding/bookbinding.a4d
 Peter Francis Kornicki, The book in Japan: a cultural history from the beginnings to the nineteenth century, Leiden: Brill, 1998.
 Kōjirō Ikegami and Barbara B. Stephan, Japanese Bookbinding: Instructions from a Master Craftsman, New York: Weatherhill, 1986.