Creep!

30 Apr

Hello all!

So, what is ‘creep’ ?

(yes, we all know of the Radiohead song and that weird bloke over there . . .)

and how do we get over the issues?

(This is a long one but I hope it helps!)

Creep occurs in saddle-stitched jobs (See Top Tip below though) where the sections/page spreads within the cover naturally move away from the spine. See this pic . . . exaggerated for effect:

When trimmed flush, the page margins are affected as the pages within get gradually narrower.

With saddle stitched jobs (especially those chunky beasts), although the finished article looks lovely and flush, the inner pages are actually smaller. Quite simply, if you grab a saddle-stitched job and pull out the central 4pp section,  you will see how much smaller it is from the ‘finished size’ of the job:

Unless creep is compensated for’ it can have a major impact on the margins and page layout.

Creep Allowance (sometimes called ‘shingling’ or ‘feathering’)

There are essentially THREE methods of creep allowance and the amount applied will vary and depend on the number of pages and the thickness of material:

– Manual Adjustment

– Page Offsetting

– Page Scaling

The next image shows a typical CENTRE SPREAD page layout that has had NO allowance made. Indications are shown where the page will be trimmed and the affect is has on the design:

Manual Adjustment

This is a very arduous procedure where, using a creep calculation factor, elements of the design are moved inwards, away from the foredge in tiny increments. Another way to put this is that each of the outer page margins will have to be manually tweaked. The closer the page is to the centre of the book, the bigger the adjustment is required. (This creates ‘progressive margins’) The example shown is a 56pp job so – Page 1 and 56 – will need a margin increase of 0.18mm; page 2 and 55 will need 0.36mm; page 3 and 54 – 0.54mm; page 4 and 53 – 0.72mm and so on in incremental multiples of the creep factor 0.18mm.                           Complicated? Hell yeah!

So where did we get the 0.18mm ‘creep factor’ from??

The Creep Factor is worked out as follows: Divide total number of TEXT pages by 4. Then multiply this number by the paper thickness (BUT, we also need to consider the ‘fold loss’ too. Another complicated issue but we find by adding 50% to the page thickness works very accurately.)  56pp divided by 4 = 14. Paper thickness 0.121mm PLUS 50% = 0.18mm. 14 x 0.18m = 2.52mm. 2.52mm is the TOTAL creep factor but adjust the margins progressively by 0.18mm. Don’t forget to ‘allow’ for the Cover – if your cover is a 300gsm, 0.28mm thick board, then your initial TEXT margin should start off ‘plus’ this amount . . . IGNORE the 50% fold loss. So if your initial margin is 5mm, you should make it 5.28mm and then apply the text creep adjustment from there. You do not need to adjust the cover margin. It can be left at your initial 5mm, for example.

You’ll be really pleased to know some printers (like good old Dayfold of course) have automatic methods to allow for creep.

Creep Allowance by Page Offsetting

Page offsetting works by ‘the system’ moving page elements inwards progressively. While this works well for the outer margin elements, there is a fundamental problem as the image above demonstrates.

Creep Allowance by Page Scaling

This is really effective:

Page Scaling works by ‘the system’ reducing the page elements in size horizontally. It is a tiny scaling, yes, distortion if you like but it is barely noticeable if at all. The ‘spec’ shown in the image above is pretty extreme to emphasise the effect. This is the system that we use at Dayfold and we never have any issues at all with ‘over-distortion’. It works extremely well and is so much better than both Page Offsetting and the highly complex and laborious Manual Method!

TOP TIP: If your job is Section Sewn/Case Bound or Burst Bound then creep WILL occur here too (within the sections) so again, it may need to be compensated for. Creep in small, thin sections will be quite minimal, so you may ‘get away with it’! However, if the stock is fairly thick or the pages are folded/sewn as more than 8pp sections, then creep allowance should be considered. On these occasions, it is certainly worth leaving any creep adjustment to the printer as you may not know how they plan to fold the job – ie whether they are folding as 8pp or 16pp sections for example.

TOP TIP: If YOU have manually adjusted your work, you must tell your printer (otherwise, they may apply one of the above ‘system’ methods . . . on top of yours!)

It’s highly unlikely that your printer will manually adjust for creep gratis. It is a very timely job so if they don’t have a method of adjustment like the above, it will be down to you to fix, or perhaps you should give us a bell 😉

I hope this is useful – as usual, please do get in touch if you need help or clarification.

With thanks to Matthew Robinson, Dayfold’s pre-press guru, for his help with this.

Best

CP

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6 Responses to “Creep!”

  1. woot design May 6, 2010 at 1:53 pm #

    Really useful article, thanks. I’m currently putting together a personal project which will be printed as 2x 64pp A5 booklets. I need to produce them as cheaply as possible, so can’t afford perfect binding. My printers keep advising me there’ll be too much creep, I said I’d design to accomodate it – this article is exactly what I need, so thank you Dayfold :o)

    • chrisdayfold May 6, 2010 at 2:12 pm #

      Pleasure indeed. Glad it was of help. Creep can be a tricky thing. More than happy to help with a quote of course? 😉
      Regs
      Chris

  2. pete May 27, 2010 at 9:43 am #

    Nice to see the skills are still in the trade.
    very useful and well explained.

    • chrisdayfold May 27, 2010 at 9:59 am #

      Thanks Pete. Useful feedback . . . How do you guys allow for creep?

      • pete May 27, 2010 at 10:09 am #

        with the wonders of modern science.
        On the Xeikon we set the number of pages, select whether we need to go inward or outward. The clever bit is that we can tell the machine the paper thickness manually and that is then set for the job stock or let the machine calculate the thickness and then it will alter the creep to the stock on the press, clever or wot.The Xeikon measures the stock anyway to keep registration, so somebody must have had a good think about it when the software was created.

        Pete

      • chrisdayfold May 27, 2010 at 6:35 pm #

        Sounds great Pete . . . does the system scale or offset?

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