An Introduction to Book Printing

Report of a tour of
BPA Print Group,
11 Evans Street, Burwood
Saturday, 13 March 2004

BPA Print Group specialises in book manufacturing. They have several divisions covering a wide range of printing services. In Evans Street there is BPA itself which is the book manufacturing division and incorporates BPA Digital; Superprint, a commercial printer; and The Bindery in which they have a major share.

Digitisation

Digitisation in printing means that anyone with a word processor and a printer can be a publisher. In the trade it means that printing now goes directly from its inception on the computer to the plate and everything originates on disk. All publications should now be presented in PDF format (Portable Document Format). In a PDF file each page is independent so the pages can be easily manipulated for imposition (see below) and any changes that need to be made will only affect a single page. Digitisation also shortens lead-time so that a publication can go from publisher to printer to bookstore in a matter of weeks.

Planning Division

The Planning Division carries out the imposition of the publication. Imposition is the process in which pages of the publication are laid out on a large sheet of paper in sets, generally of 8, 16, or 32 pages. When this large page is printed on both sides, it is folded to form a section. Imposition lays out the pages so that they are in the correct order when the section is folded.

Imposition has several implications in the design of the book and the publisher should talk to the printer about this when planning the book. For instance, if the publication is mainly in B& W with a few colour illustrations, the book should be designed so that all colour illustrations are on the same side of the sheet to reduce the need to use four colour printers.

Colour Printing

The publisher should also consult the printer about the use of colour, as this is a complicated process. The main problem related to digitisation is that printing uses a four -colour process – CMYK (Cyan, Magenta, Yellow and Black) – while the colours seen on screen are made up of three colours – RGB (Red, Green and Blue). Therefore it is difficult to match the colours we see on the screen and the colour that will eventually be printed. If getting the exact colour is important, eg for a well known company logo, then it must be matched with a pantone (specialised ink mix formula) swatch which the printer has in PMS books of colour samples.

Prepress

Once imposition is complete a set of proofs can then be produced. These are checked by the publisher. If there are any changes they must be made at this point. The publisher should check the text, page numbers, colour etc. With PDF technology, it is a simple matter to make changes on a single page without interfering with the layout of the rest of the publication.

Once the proofs are signed off by the publisher, the plates can be produced. As the plates are produced from the same computer files which produce the proofs, there should be no differences between the proof and the final product. The only differences may be in colour resolution as the proofs are usually a lower resolution than the final product.

Printing Plates

A plate is produced for each colour on that sheet (1, 2 or 4). The plate can be made from metal or polymer. (Metal plates are more reliable than polymer, but also more expensive. However they can be recycled.) First, the image is projected onto the plate. Then the image is baked onto the plate in an oven. Finally the plate is washed in a range of chemicals (similar to developing photographic film). The plates are kept for up to twelve months in case of reprints, but from then begin to deteriorate and must be replaced.

Printing

BPA mostly uses offset printing although they do have digital printing facilities (see below). Their printers are sheet fed as opposed to web fed. Sheet fed printers are used in better quality printing and print on single sheets of A 1 paper. They give better results and choice of page size and shape. Web fed printers print directly from a large roll of paper and are used for newspapers and magazines etc and mass market paperbacks. They are limited in the range of page sizes and shapes they can offer.

There are two types of presses at BPA – one-over-one and two-over-two. All are perfecting presses ie they can line up the plates so that both sides of the sheet are printed exactly in sync. Plates are manually applied and changed by the operators.

The one-over-one press has two sections. It can be set up to print two colours so the one side of the sheet will go through twice, once for each colour; or it can be set up to print double-sided so the sheet is printed on one side, turned over in the printer and printed on the other side. Batches of single sided sheets are then turned over manually and printed on the other side, either in the same press or elsewhere eg four-colour press.

The two-over-two press has five sections. It can be set up to print two colours on one side and then again on the other. Generally it is used for four-colour printing. The colours are usually set up in the order of black, magenta, cyan and yellow. The fifth section may be used for overprinting (this may entail a change in the order of the colours); for a fifth, specially mixed, colour; or for a varnish or a shiner to lift type.

Digital Printing

BPA have invested in a digital printer, as there is a demand from the publishing industry for short run printing. It can be used to produce short runs for self-publishers, to reissue out of print books, especially in the academic field, or to produce pre-launch copies for large publishers for sales and promotional purposes.

The digital printer does not use plates, but, using PDF technology, can print directly from disk. Therefore a book need never be out of print if it is on an electronic file. It is a one colour (ie B& W), web fed printer which offers a rage of page shapes and sizes. It also prints in sections, double-sided and folds the sections. The sections are presented in order ready for binding. There is also a perfect binder (see below) on site so that the books can be bound as they come off the presses. The division can be locked off and used for security printing such as exam paper.

The digital printer can produce as few as one copy at a time. However, the size of the run is a major factor in the cost. It is recommended for print runs in the hundreds (as opposed to in the thousands for offset printing.) As it is a one colour printer, coloured covers and insets must be produced elsewhere, either on the four-colour offset printers or off the premises on colour digital. It is sometimes possible for a small cover to be produced on the same sheet as another cover going through at the time. However, it is recommended that the publisher order enough covers for the entire life of the book, as it is the most expensive element of the book. The difference in cost in producing a thousand over a hundred copies in one run is minimal, but the cost of a new run will be much greater.

Binding

All of BPA's output (including its digital printing) can be sent across the street to The Bindery to be bound. The Bindery offers perfect and burst binding, thread sealing, section-sewn binding and case binding. In perfect binding, the edges of the folded pages are trimmed, so that individual pages are glued to the spine of the cover. This is the weakest form of binding. In burst binding the sections are kept together but the edges are perforated to take up the glue. In thread sealing, threads are punched through the edge of the sections and the ends of the threads also take up the glue. In section-sewn binding, each section is sewn along the edge and then the sections are sewn together. Thread sealing adds about 10% to the cost of binding while, section-sewn binding adds about 30-40%. Case binding is hardback binding and any of these methods can be applied with soft or hardback covers. All these options are also available for digitally printed books.

Each section of the book has been carefully labelled in the print works and comes across on palettes by forklift. The sections then go to the folding machine to be folded. From there they are taken to the hoppers to be collated. Strung above the hoppers is what is known as a washing line. Here a sample of each section is hung in the correct order. Referring to these samples, the operators know which section goes in which hopper and which way up. From the collator the sections are passed down a vibrator to be lined up. Each completed book is then clamped and the hot glue is applied, ready to be attached to the cover. (see above) In the case of soft covered books, the covers and pages are then trimmed together to ensure they are the same size.

In the case of case binding (hardback) the pages would be trimmed to size before binding. A hardback cover is basically two pieces of cardboard to which are glued the cloth, pre-printed covers. The end papers (the two pages at the beginning and end of the book, usually blank but can be printed) ie the first and last sections of the book, are glued to the inside covers, then the rest of the sections are added. Cloth head and tail bands are then applied to the inside edges of the book as a finishing touch. Case-binding can add another 10-15% to the cost of binding.

Print Overruns

With each print run, a certain percentage of extra copies (eg 300 for a run of 2000) are built into the cost. These extra copies are used up in ensuring that the print run is of the highest standard. Most of these copies are used as 'setters', waste copies that are used to adjust the various machines to the right setting eg to ensure that the printers are properly inked up, that the folding machine is correctly aligned, that the trimmer is correctly calibrated. Any overrun copies remaining at the end of the printing process belong to the publisher.

Ecological paper

Most large publishers insist on ecologically sustainable paper stocks being used in their publications, so it behoves a printer like BPA to ensure that they use such paper, even though it is more expensive, in order to keep these important clients. BPA must have the necessary paperwork to prove the origin of each batch of paper they use.

A Parting Word

As each stage of the printing process is complex, it is imperative that publishers discuss all their needs, and the needs of their readers, with the printer at the earliest planning stage of their publication. Such decisions as the size of the book, the number of pages, the grade of paper used, the colour and number of illustrations, the type of binding, all have implications in the process and in the final quality and cost of the publication.