Book folding is the stage of the

book A book is a medium for recording information in the form of writing or images, typically composed of many pages (made of papyrus, parchment, vellum, or paper) bound together and protected by a cover. The technical term for this physi ...

production process in which the

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s of the book are folded after

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ...

and before binding. Until the middle of the 19th century, book folding was done by hand, and was a trade. In the 1880s and 1890s, book folding machines by Brown and Dexter came onto the market, and by the 1910s hand-folding was rare, with one publisher declaring them to be "practically obsolete" in 1914. The folding process is also necessary to produce print products other than books—for instance mailings, magazines, leaflets etc.

Hand folding

Folding machines

Two main types of mechanisms are commonly employed in

folding machine A folding machine is a machine used primarily for the folding of paper. Folding is the sharp-edged bending of paper webs or sheets under pressure at a prepared or unprepared bending point along a straight line according to specified dimensions and ...

s: buckle folders and knife folders.

Buckle folder

In a buckle folder, the paper is first passed through 2 spinning rollers, which feed the paper into a pair of guide plates that redirect the paper at a slight angle, bending the paper. At the far end of the guide plates is a "paper stop". As the rollers continue to spin, the paper continues to slide in between the guides until it hits the paper stop, then, having nowhere else to go, buckles at the interface between the rollers and the angled guides. As the rollers continue to spin, the buckle increases, until it is eventually caught by a pair of "nip" rollers, which pull the buckle in and compresses and flattens it into a neat crease. Adjusting the paper stop in a buckle folder determines where the fold will be placed. Also, a buckle folder may contain only 3 rollers, with one shared by both the input rollers and the nip rollers. Although buckle folders are fast, simple, efficient, and have small folding tolerances, they are not suitable for substrate of very low (<40g/m²) or very heavy paper grammage (>120g/m²).

Knife folder

In a knife folder, a sheet of paper is fed horizontally over 2 unpowered rollers until it hits a paper stop, at which point a dull blade pushes down on the paper and in between the 2 rollers to create the fold. Although the knife folder is slower than buckle folders, it is more precise and can handle extreme grammages very well. It also has small folding tolerances, but is a more complex machine.

Folding variants

Parallel folds

Folding a paper more than once in the same direction (i.e. with parallel creases) is called parallel folding. Common examples of this are the half fold, letter fold, gate fold, and Z-fold.

Cross folds

A cross fold is when a paper is folded once, then rotated

90 degrees 9 (nine) is the natural number following and preceding . Evolution of the Arabic digit In the beginning, various Indians wrote a digit 9 similar in shape to the modern closing question mark without the bottom dot. The Kshatrapa, Andhra and ...

and folded again. The creases therefore cross each other at right angles. The most basic cross fold is the French fold, or right-angle fold. Other examples include the 16-page broadside and the 12-page letter.

References

{{DEFAULTSORT:Book Folding Book arts Print production