Books are constructed in several ways. Many repair materials work best on certain kinds of paper or in specific parts of a book. “The right tool for the right job” is an axiom that applies to book binding as well as other fields. Having a few specialized tools and understanding how to use them will save you time and energy. Here are some of the parts of a book you may get very familiar with when you start doing your own book repairs.

Text block – The pages of a book, whether they are sewn or glued together, are called the text block.
Case – The covers of a book are called the case. The case is made of
the front cover, the spine and the back cover.
Signatures – When the text block is sewn, the pages are gathered together in groups; then each group is folded in half. A group of folded pages is called a section or signature and is usually four to eight pieces of paper (four pieces of folded paper equals sixteen numbered pages).Books that are constructed of sewn signatures tend to function best because the pages are securely attached to one another and they open flat. Modern manufacturing techniques enable book manufacturers to create a text block with signatures, cut small notches in the folded edge and insert glue to hold the pages together instead of sewing thread. These books look like they are sewn, but they are not. Open the text block to the center of a signature and look for the thread, if it’s not there, the book is glued.

Text blocks in loose sheets – Text blocks can also be single sheets glued together in a process called adhesive, perfect, or fan binding. In this process, fast drying glue is applied to the spine of the text block. Adhesives that dry very quickly are often brittle and that is why the spine of a book cracks when the book is opened. Once the spine glue is cracked, the pages will begin to fall out. In addition to the problem of brittle glue, there is often very little glue attaching each page to the adjoining pages. When the glue is only in contact with the very thin edge of each sheet of paper, pages can easily separate over time.

Double-Fan-bindingSingle and double fan binding – ln single-fan binding, the pages of the text block are fanned in one direction and glued along that fanned edge. ln this style of binding, a thin line of glue penetrates the inner margin of each page, not just the spine edge.

Double-fan adhesive binding goes another step beyond single-fan
binding. After the pages are fanned in one direction and glued, they are also fanned in the opposite direction and glued along the second fanned edge.
Double-fan binding applies glue on the inner margin of each side of the page, not just on the spine edge or the inner margin of one side of the paper. It is much stronger than single-fan binding.
When professional binders bind a book using double fan binding, they use adhesives that dry slowly and are flexible. In addition, they usually reinforce the spine edge of the adhesive bound text block with cloth and paper so it is stronger and the text block opens flat.
Oversewn text blocks – Before craftsmen began to fan bind books, the most common form of binding was oversewing. In the oversewing process, the folds of the signatures are trimmed off and the pages of the text block are oversewn to one another with a diagonal whip stitch. Since the sewing threads tend to pierce deep into the inner margin, the pages are restricted from turning easily. Oversewing is a strong form of binding, but it is often so strong that over time the pages can break out of the binding as they are forced to turn against the sewing threads. Oversewn books may not be candidates for rebinding since much of the inner margin was trimmed off or damaged by the oversewing threads. Books should not be oversewn unless they are very heavy and have wide gutter margins to accommodate the sewing threads.
Flat back text blocks – Flat back books are a type of binding which has a flat text block spine. The case spine of flat back books is usually a piece of book board covered with book cloth. The spines of flat back text blocks have a tendency to become concave over time. To prevent this, the spine of the text block can be rounded and backed.
Rounded and Backed Text Blocks -Text blocks are rounded and backed to shape the flat spine of a text block into a curved spine with shoulders. RoundingRounding a text block is the process of molding the spine of a text block into an arc of approximately one third of a circle. Rounding takes place after the pages of the text block are attached to one another by sewing or gluing. A light coat of adhesive is applied to the spine which is then worked into shape with light pressure applied with your fingers or a special hammer called a backing hammer.
BackingBacking is the process of shaping a ridge or shoulder on each side of the spine of a text block prior to attaching the spine lining material. Using a backing hammer, the folds of each signature or glued pages are bent over from the center to the left and right until shoulders are formed against which the boards will fit. The width of the shoulders is determined by the thickness of the cover boards. In addition to providing space for the cover boards, backing also distributes the swell caused by the sewing threads or adhesive and helps maintain the round of the text block over time.
Book case construction – Regardless of how the text block is assembled, modern books are usually manufactured in two stages. The text block is constructed in one operation where the pages are attached to one another, the spine covered with a cloth liner, called crash, and a paper spine liner is added over that. The book case, consisting of a front cover, a spine and a back cover, is constructed separately in a second operation and the two parts of the book are attached by gluing the crash and end papers to the case covers. The crash holds the text block into the case while the end papers cover up the crash.

Time for a break – part 2 will follow!