Terms of Book and Printing#

This document describes basic introduction to bookbinding and printing. See detailed descriptions, algorithms and implementations in each document of Features.

Shape and Structure of Book#

Bookbinding is a work of binding materials to make a book. Including historical approach, rolled scroll can be included, but in this chapter common style of book will be treated. It is called Codex style. Codex is In a view of bookbinding, book, codex, is an object which is composed of multiple signature.

Signature#

The signature is a contents block of a book, pamphlet, or booklet. That is, a group of sheets not separated by its contents, but a prefixed number of sheets. There are some synonyms, section, and gathering. This document will use signature.

Pages compose a signature and the signatures compose a book, booklet, …, et cetera. A single page can become a signature and a single singnature can compose a single book or booklet, (usually booklet).

Why we need signature in bookbinding?#

If you have made ring or stapler binding in home or local printing center, you might not think it is not needed to prepare content block by prefixed number of leaves. However, if pages exceeds more than hundreds, you cannot prepare all contents to bind at once. With some efforts, it might be possible but it is a waste of time and finance resources not only for manufacturers but also for hobbists.

Therefore, people make small sections first and bind them at final stage for large number of pages. In addition, there is a manufacturing reason. Cutting and folding are always easier than combining and gluing materials in manufacture process. Consequently, printing with raw paper roll and cutting them is more effciency than gathering small printed papers. Even you are printing manuscripts with home printer, folio type printing can reduce significant efforts than single leaf printing in bookbinding. That is why using a signature in bookbinding.

Types of signature#

By the number of leaves#

Commonly used types are next,

Name	Leaves
folio	2
quartos	4
octavo	8
duodecimo(12mo)	24
16mo	32
18mo	36
32mo	64
64mo	128

Above names just indicate leaves of each signature but they have a meaning of booksize. They are determined with their country’s standard the raw paper size, if there is no prior name, or forehead paper name. For example, Crown quartos size, 195 x 254 (mm), is a quarter of Crown paper size, 508 x 381 (mm).

Imposition#

The imposition is a locating work of pages to paper and the result of the work. Unless you binding book in old Asia style (their method can use single paper as a basic signature), you must print the signature considering fold action. This is why the manuscript for a book should have a number of pages which is a multiple of 4.

By the folding direction and order, its imposition layout on larger paper is vary. If you have an experience of map folding subject in origami geometry, it will be friendly. However, it is not as complex as them, because of the characteristic of signature folding. All types of signature after folding must be its one side covers all centers of connected two leaves. This makes permitted folding to be restricted next.

Signature folding

Every creases must be perpendicular or parallel to each other.
Each fold must be in next two cases.
1. (*) Perpendicular to the previous fold line and fold all layer at once.
2. (**), Parallel to the previous fold line and fold all layer at once.
3. (***), Parallel to the previous fold line. If fold partial layers than the other must be folded in same stage. Sequential parallel foldings can include half folding of all layer, in this case, there must be other parallel folding steps.
The last fold must be (*) or (**) type.

(*), (**) : Doubling previous grids.

(***) : \(k\) number of parallel partial folding makes \({} \times (k+1)\) grids.

Standard type#

Repetation of 1st type folding only. Leaves = \(2^n\), 2, 4, 8, 16, 32, 64, 128, … .

Extended type#

At least one step is 2nd type folding, this allows us to compose addtional prime numbers for divisor of leaves number.

Example: 6, 12

6 leaves:

Fold \(x\)-direction - start
Parallel fold \(x\)-direction - end \({} \times 3\)
Perpendicular fold \(y\)-direction - start -end \({} \times 2\)

\(6 = 1 \times 3 \times 2\)

Signature composition#

As written above, a signature is governed by its number of sheets. Single paper signature is \(2\) sheets signature with dual side printing. The number of sheets of signature must be a multiple of \(4\), practically considering fold. Therefore, permitted numbers are \(4, 8, 16, 32, 64\) and \(12, 24\). \(12, 24\) signatures differ in its fold progress with \(4, 8, 16, 32, 64\). Bigger sheets can be used \(>64\) to make a single signature, but it is not practical.

There are two types of methods to combine signatures, inserting and gathering. There are no differences among them after cutting their edges, but the order of pages are differ by type. The gathering does not affect to order of each signature but inserting does to match the correct ordering of pages.

The \(n\) sheets signature is composed of \(i\) time inserted \(f\) sheets signature.

\[n = i \times f.\]

If \(i = 1\), the signautre is complete itself.

For example, \(16\) sheets signature has next variation for same types.

\(1 \times 16\)
\(2 \times 8\)
\(4 \times 4\)

If we permit combination of difference types.

\([4, 4, 8]\)
\([4, 8, 4]\)
\([8, 4, 4]\)

Ordering of combination in \([,]\) is important. The latter cases are called deep type signature in book of T.B. Wiliams (1895). With deep type, we can make every even number signature for example,

\[40 = 32 + 8 = 4 + 4+ 4+ ... +4 = 16 + 16 + 8, ...\]

Riffle direction#

Riffle direction is a direction of riffling while you read the contents of a book. It depends on the reading direction of language. The most common direction is a horizontal, from left top to right bottom(HLTRB) direction. There were various reading directions by the language system. Most of them are not used in the recent era, but from left to right reading direction frequently used in many situations more than people think.

Belows are uncommon example languages in reading direction.

Asia, Korea, Japan, China … etc

East Asians used VRTLB (vertical, from right top to left bottom) system. Now, vertical writing is rarely seen in modern texts in Asia (it is different by the country), but as a design or a research work, they are still adopted in many works. For example, some Japanese mangas use vertical writing in their speech bubbles. There is a good different point in the speech bubble by the writing direction in Japan and Korea. Japan’s speech bubbles are vertically long while Korea’s are horizontally long. Korea also uses vertical writing once, but in the modern era is not as popular as in Japan. This difference is affecting to their speech bubble shape in comics. It is one example that how the cultural difference, in this case writing direction, is visually expressed.
Hebrew and Arabic

RL system
Ancient Egyt

Their system was very special. They used both direction LR and RL. The same characters can be written symmetrically by the direction.
Elder Island script, Ogham scripts

It also has an abnormal direction. Its direction is vertically from bottom to top.

From top to bottom, or from bottom to top are not affected by the order of pages if you riffle horizontally. However, whether the reading direction is LR or RL affects the page ordering considering reading efficiency.

The default setting of HornPenguin Booklet is a LR direction and supports RL.

Supporting RL is not complicated. Just reverse order the pages before applying to rearrange transformation to the pages.

Printing markers#

Signature proof#

Signature proof is a ordering proof marker on the spine of signatures. It helps for people to arrange the signatures in right order and check missing signatures.

Crop marker#

Trim line indicator.

Registration marker#

Registration marker is added to check the registration of color printing of printing machine. Its color looks like the normal black color (CMYK(0, 0, 0, 1)) but actually, it is a special color called registration black, CMYK code is (1, 1, 1, 0). If they are perfectly fitted, it will look like normal black color.