Flexible binding

A flexible binding of spine construction where the covering material, usually leather, is adhered directly to the spine of the book block or to the lining on the spine. It is also known as a tight back. It is called "flexible" not because it makes the entire book more flexible, but because the spine's covering material moves with the spine as it folds into a concave shape as the book is opened. It is commonly used when sewing on exposed cords. This style of binding was common in England in the 17th and late 18th centuries. 

Flexible binding (= tight back) 이란, 표지 (일반적으로 가죽)가 본문의 책등에 직접 혹은 책등 안감에 직접 부착되는 구조이다. 이는 책을 펼치면 책등이 오목한 모양으로 접히면서 열리기 때문에 '유연한' 제본법이라 불리게 되었다.17세기부터 18세기 말까지 영국의 거의 모든 책은 이 방식으로 제본되었다. 

First, the textblock composed of 16 sections was sewn on five cords. Then, a mixture of EVA and wheat starch paste was applied (but not cords) to consolidate the spine and hold the sections together. Once the adhesive is completely dry, the textblock was rounded and backed to create a shoulder. Next, two colour endbands were sewn. 

Spine lining was adhered (mull, kraft paper). Then, board sanding! the spine side of the board was sanded to get a nice smooth edge. The exterior and interior channels were marked on the board and cut, and punched holes to accommodate cords. 

In order for the cords to lace in the boards, it is necessary to fray them out, and they were saturated in a wheat starch paste to make the threading easier. The cords were threaded through the cover, and when the slips were laced in, the cords were hammered and sanded to remove bulks. Once the boards were fully attached, the covering leather that had been pared was adhered with wheat starch paste. Then the cords tied up the covering skin on each side of the raised bands between pairs of boards, and the cords were strung across the spine of the book to hold the leather in shape as it dries.