基本的な装訂の種類3 -粘葉装

Next let us look at detchōsō (“pasted-leaf”) binding. The leaves are joined together with glue, as with scrolls, but the area where the glue is applied is different. Each leaf is first folded in two and pasted to the next leaf near the crease. When you look at it from the side the shape of each leaf resembles a “y”. The area where the glue is applied is called norishiro. The inner side of each folded leaf opens completely, but the outer side which is connected to the next leaf only opens up to the glued part. Then again there is a leaf that opens up completely followed by one ―the glue has come off here―that only opens partially.

This alternating of fully opening and partially opening two-page spreads is the distinctive characteristic of the detchōsō binding. In terms of structure and how you turn the pages, it is very similar to modern books and in fact it is considered the oldest type of book-style binding. However, one shortcoming is that, as you have just seen, the glue tends to come off easily causing the pages to fall apart. Another major defect is that―please look at this―this is a very old example of detchōsō binding, as you can see, there are many small holes. They are especially numerous in this area here. What these are is wormholes made by insects that feed on paper.

Insects that feed of paper are called shimi in Japanese, but here the culprit is not shimi. A family of insects called shibamushi or shibanmushi (Anobiidae) which have a hard shell and resemble the rhinoceros beetle lay their eggs on the paper and the small larvae then feed on the paper to grow. They don’t dislike paper but their favorite target is the glued area, which is the most nutritious. Therefore, this is the most easily damaged part. And of course, when this part is damaged, the entire book falls apart like this. So this type of binding presents a number of major flaws. Which is why starting from around the 13th century, it gradually fell into disuse.

Having said that, the famous monk Kūkai used the detchōsō format for the Sanjujō sasshi (the Thirty Books), the set of latest Buddhist scriptures that he brought back from China and which are now designated a National Treasure. In books brought to Japan from China ―this has to do with the type of paper― there is writing only on the inner side of each folded leaf and the pasted side is left blank. Detchōsō books made in Japan, however, usually have writing on both sides of the leaf. Because of Kūkai’s legacy, the detchōsō format continued to be used within the Shingon sect of Buddhism up until the modern period, so long after everybody else had stopped using it.

And here I conclude my explanation of pasted-leaf binding.