Posted: 21st July 2020
Perfect Binding is book binding in the style of paperback books, telephone directories, magazines etc where only a short useful life is expected. Single leaved or folded sections are gathered / collated into book blocks that are fed either manually or automatically into a clamp which holds the book firmly. The perfect binding process then begins by "milling" the book spine to a rough edge, EVA hot-melt glue is applied to the spine and along the front and back edges. A creased cover is then applied and pressed firmly from below and from the sides to give the completed book its characteristic square back finish. Lastly, the top, tail and fore-edges are cut to size ideally by a three knife trimmer.
Drawn-on or Soft Cover binding is a repeat of the above process but the book blocks have been pre-sewn on a book sewing machine and the spine milling unit is switched off as it is not necessary. This process gives a stronger bind and is popular for school or trade reference books where a useful life of more than one year is required.
PUR glue is also used for a stronger, longer lasting bind or where a lay-flat book is required. This glue requires a longer curing time before three knife trimming can take place. The melting unit must also be enclosed in order to preserve the glue and prevent harmful fumes escaping. It is also more expensive than EVA glue but a thinner film thickness is required.