Book folding

Book folding is the stage of the book production process in which the pages of the book are folded after printing 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.

Folding machines

Two main types of mechanisms are commonly employed in folding machines: 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.