Quick Printing Guides – Folding

by Rich B

Introduction:

  • Folding is a method of reducing a sheet of paper down to a more usable size or shape. It’s important designers and marketers understand the issues surrounding folding and the printing process so they can design their way around potential problems.
Folding unit on 48pp printing press

A folding unit on a 48 page four colour printing press

Design Issues:

  • The more folds that are used, the greater the variation in position (register). To demonstrate the principle, fold by hand carefully, a reasonable sized sheet of paper 4 times, each time fold the longest side in half (32 pages) and see the variation at the foot. Take this variation in to consideration when designing a folded leaflet or book section; the thicker it is, the more variation there is.
  • If a design has to run across a pair of pages, try to use ‘a natural pair’ i.e. the centre of a folded section, rather than hope that an exact fit will happen when folding. For double or open gate folded leaflets, allow the design to finish short in the centre, leaving a paper gap of 3mm to 15mm. If the flap forms part of the magazine/catalogue cover one must ensure that the flap can be opened out to view once the inside sections are inserted, this usually means that the flap is about 5mm shorter than the other pages.
  • For work with multiple folds, take care that it does not become too thick or too small for the folder. As a guide the normal maximum thickness a fold unit will take is 2mm. This will give a final thickness of 4mm, so keep well under that.

Production issues:

  • For multiple fold work choose a paper that is resistant to cracking. The grain should be parallel to the fold for paper above 115gsm, above that scoring or creasing will be necessary at an extra cost. If the design has solids that bleed and they are near the edge of the printed sheet, more paper should be allowed as this can avoid problems with the edges of the sheet curling, causing spoilage and delays. If a concertina leaflet is required allow more bleed on the foredge side of the cover page, as this will need to be slightly wider to cover the folded leaves behind it. It is also good advice for most leaflets to allow greater bleeds on the front page.
  • Work that is laminated or varnished both sides may not be able to be folded, although machine varnish applied on a 5th unit of a printing machine is usually suitable for folding. Below 60gsm, folding is possible, but a higher degree of skill is required and spoilage is much greater. If edge trimming is going to be used, 10mm should be allowed. If it is possible to fold the job 2-up, then lay the plates down so they are both in the same position one way and head to foot the other way. Allow for a single cut between copies if there are no bleeds. With bleeds try to make the solids meet and allow 6mm trim out between copies.

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