Pre-press

There are many types of printer, as we have seen, but your book is being printed for the first time. Chances are, then, that it will be printed by an offset printer, taking form in a rather scary, noisy place where huge lithographic printing presses tirelessly grab, ink and eject thousands of enormous sheets of paper every minute of the working day. Hell’s kitchen is not where the work begins, however, not where the print files for your book arrive from the publisher. No, the first stop is paradise.

Behind the double doors

More than likely, your print files will be delivered to the printer via the internet (though not by e-mail; the files are usually too large). But let’s pretend in your case that everything is on a DVD coming to the printer by courier.

Today, it’s Hasan making the delivery in his brightly painted courier van. He knows where to go, skirting the tumult of the print shop, dodging a fork-lift truck loaded with paper, and arriving at reception. Mrs Khoo is on the phone and, seeing the envelope and its contents description, silently begs that Hasan deliver it directly upstairs to the pre-press department. He doesn’t mind; Mrs Khoo looks just like his auntie.

The din of the printing presses follows Hasan up the stairs but, at the top, there are double doors. Behind them, all is hushed and a shoe rack reminds Hasan to remove his shoes; this is a clean zone sealed off from not just the noise but also the dirt of the outside world.

In front of him is what looks a bit like a gamer’s paradise: a series of rooms in which he glimpses big-screened Macintosh computers and all manner of other strange equipment. Nor are the people here like the solid, chunky guys wearing overalls you see downstairs; no, frankly, they look like office workers. Indeed, some of them could be the kids you see downtown in the video game arcades and internet cafes – nerdy types.

Welcome to the pre-press department.

Plate-making

Hasan has gone now, together with his shoes, but your book files remain and already they are being loaded onto the pre-press server.

Essentially, from this point, the PDF files delivered from the publisher are prepared for printing. A key process here is imposition, whose purpose is to remap the linear sequence of pages onto giant sheets of paper that ultimately will end up as 16-page signatures. This mapping is complicated because the original pages must be scattered, turned and placed on the sheet so that, when it is printed on both sides, folded and trimmed, the 16 pages appear in their correct sequence and orientation. The following diagram probably explains this better.

Just how the whole process is achieved depends a bit on how sophisticated the printing company is. Twenty years ago it was common for the typesetter to output to film, which was then manually imposed (or ‘stripped’) on a light table to create the sheets. (Indeed, camera-ready copy was also common at this time, i.e. laser-printed pages were cropped and stuck together inside a sheet-sized frame and then filmed.) Today, however, digital processes exist that quickly and accurately automate the imposition process.

Once the sheets have been created, the final printing plates can be made. Again, traditionally this was done via an intervening step using film but increasingly the direct computer-to-plate process is used. Whatever, the end result is a metal or paper plate on which a mirror image of each book page is etched and then – by the application or repulsion of ink – reproduced as a positive image on paper during printing.

Colour

The above description implies there is only a single plate used to print each side of the signature. But, if pages are coloured (i.e. more than black, white and shades of gray), then additional plates are needed. These days, typically four plates will be used, one for each of the CMYK process colours (cyan, magenta, yellow and black [key]) on which the printed colour spectrum is based. Otherwise or in addition, spot colours (specially mixed to a specific hue) may be used.

Should multiple colour plates be needed, then colour separation of the PDF files received from the publisher will need to be done as one of the first steps. Here is an example of how this might look:

Not so fast!

Once the printing plates are ready, your book is ready to print – yes? Well no, actually, because I’ve rather jumped ahead of things. At the time the signature files are created, specimen proofs are printed off and sent to the publisher for approval. I’ll describe these printer’s proofs in greater detail in my next post.

(Post #5 of the Printing section of a lengthy series on the book production process, the first post of which is here.)

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3 Responses to Pre-press

  1. […] no, wait a moment. As mentioned in my last post, specimen proofs must first be printed off and sent to your publisher for approval. These allow […]

  2. […] Earlier, I described the hushed, clean zone of the pre-press department. Beyond the double doors, it is a different, almost primitive world with scenes straight out of the devil’s kitchen, a place moreover that often smells like a glue-sniffers’ convention. But above all else, this is a world coloured by one thing: the noise of many huge lithographic printing presses tirelessly grabbing, inking and ejecting thousands of enormous sheets of paper. […]

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