Tuesday, 17 November 2015

What is ...Creep?

What is ...Number 23
Regular followers of this blog will know that in the middle of the month, I publish a "What is ....? post. The article covers various aspects of paper, printing and finishing in greater depth. However, many of these subjects are complex, so these posts are only intended to be a brief introduction to the topic.

What is ...Creep?

Because most bound publications are produced by folding large sheets down to a smaller size and forming multiples of 4pp sections, the number of printed pages of any document will start to affect the physical properties and the position of the printed matter. The inner sections will start to protrude beyond the outer pages - see diagram below.

If adjustment is not made, printed matter will get too close to the trimmed edge. To demonstrate, here is a 32pp saddle stitched, self cover brochure, which I wrote about last year: http://justinsamazingworldatfennerpaper.blogspot.co.uk/2014/02/breaking-down-barriers.html

If I hold the booklet open in the middle, you can see with the image below the difference in the width of the page size, which has effectively become staggered because of the straight cut edge.
To demonstrate further I've taken the book apart. With the spines in the same position I've laid the centre spread underneath the cover (below image). The finished size of the book is 235x165mm. The total width of the double page spread of the cover is 331mm, the total width of the centre spread is 327mm, so the difference pictured below is 2mm:
Click on images to enlarge
Creep Allowance is also known as "feathering" or "shingling" and unless an allowance is made for creep it can have a major impact on the margins and page layout.

There are three methods of creep allowance:
  • Manual Adjustment
  • Page Offsetting
  • Page Scaling
All the methods depend on the number of pages and the thickness of the material. Manual Adjustment is a very arduous procedure which involves a mathematical formula which calculates by how much the design elements are moved away from the foredge in tiny increments and the artwork is then adjusted manually. Creep Allowance by Page Offsetting is where a program has been written which moves page elements inwards progressively but can result with problems in the spine.

Creep Allowance by Page Scaling is the preferred method by printers. It works by having a program which reduces the page elements in size horizontally. It is a scaling program which inevitably is a distortion of the original but is the most effective automatic system.

As mentioned earlier, if the project is section sewn or even perfect bound the same issues are a factor as they are all made using folded sheets of paper. It may be less of an issue if a project is made using 16pp sections but with a bulky material, for instance, it could be a real issue.

In my experience, the first time people come across the term 'creep' (in printing) is when there is a production problem. Generally, a job has been printed and finished, then someone spots the issue (usually type or images getting to close to the foredge) and then someone will start talking about creep ...this is not helpful if you have never heard of it! Typically the event I've just described is usually followed with finger pointing and people looking for someone to blame.

Creep Allowance is something that should be discussed rather than ignored until there is a problem. Responsibility must be assumed and agreement should be reached at the start of a project about who (designer or printer) will make the adjustments. My advice is: Talk about it!
Posted by Justin Hobson 17.11.2015

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