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“Spot” the difference of soft light with overprint preview

I recently found myself being the “bad guy” after having to instruct a customer to resupply their artwork given that many of the effects applied to the pictures in InDesign would not print as desired.

In short, the artwork was an annual report printed in full colour plus a metallic silver spot colour. Originally supplied PDF only, everything looked fine on first glance with the overprint preview off. However, while the document was being manually preflighted using Acrobat’s Output Preview, I had noticed that a greyscale-like effect on the silver had disappeared once I had entered the Output Preview. Concerned, I restarted Acrobat to make sure the glitch was not software related, but again the same thing appeared. This happened on several machines and it soon became apparent that the artwork would in fact print as it appeared in Output Preview rather than the normal preview.

The customer was then contacted and informed of the situation. After replying that the artwork looked fine on his screen, the customer was then instructed to turn the overprint preview on within InDesign, and lo and behold… he began to see what I saw. He then told me he had used the soft light effect.

To demonstrate the phenomenon, I have created a new InDesign file with five elements: a rectangle coloured with Pantone 871C; a rectangle coloured with the default green which ships with InDesign; a stock photo with the soft light effect applied , and two captions of the colours in the rectangles. In the before image, the Separations preview is turned off.

and this is how the InDesign file looked after the separations preview was turned on:

resulting in the image disappearing from Pantone 871C rectangle. However, the image still appears over the process green rectangle.

Ultimately, this means that the effect is only reproducable over process colour, and not spot colour, regardless whether it is metallic or not.

Interestingly as well was the fact that in Live preflight, there was no error warning of this particular feature of the soft light effect, so if I was purely to obey the live preflight and not check my file with the separations preview or overprint preview, this would have been completely missed.

The lesson here? Always check artwork using the separations preview to make sure the artwork will appear as designed, and that some effects will work in process only.

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Don’t impose your art on me!

Imposition (a process of arranging pages in a certain order on a larger sheet so that, once complete, the artwork is finished in the correct order) is an essential part of printing whether the artwork is a book, CD face, business cards or a t-shirt design.

This is a task which should always be performed by the printer, given that the printer is the only one who will know:

  • the sheet size the artwork will be printed on;
  • how the artwork will be duplexed;
  • the amount of pages to impose on a sheet, and the pattern or sequence;
  • the grain direction of the paper;
  • any mechanical features required in the imposition, such as quiet areas or laps;

Given the amount of information needed prior to creating an imposition, customers which choose to impose their own artwork effectively make the printer’s job a lot harder.

Often, printers will have to take client-prepared impositions and break them back into single pages so that the artwork can be reimposed to the printer’s specifications rather than how the client had prepared the imposition.

This can be complicated further if, once proofed, the customer resupplies the artwork with alterations, but in same – or different – imposition.

Extracting pages from imposed artwork is all billable time.

Ideally, artwork should normally be provided as single pages prepared to the correct size so that the printer can impose the artwork as they see fit.

Printers worth their salt will normally use specific software dedicated to impositions such as Kodak Preps or Dynagram Dynastrip, or plug-ins to layout software such as Quite Imposition.

The above also applies for book artwork. Again, clients providing either PDFs as readers spreads or printers pairs are making their printer’s work harder to do as they will have to break the pairs into single pages for imposition.

Put simply, there is no advantage in imposing artwork prior to submitting to the printer – leave this step to them.

Too close for comfort… and crop marks

When preparing PDFs for commercial printers via Adobe InDesign, be aware of how far away any crop marks generated by the export will be from the trim-size of the finished artwork.

It is not uncommon for printers to ask their clients to prepare PDFs to certain specifications. Some instruct their customers to use standard defaults such as PDF/X-3: 2002, some will have their own step-by-step instructions to the export dialog boxes, while others are more sophisticated and offer pre-saved joboptions files for clients to download and install.

Pre-saved joboptions files are my preference given that these settings supplied by printers to their customers are normally the same settings that the art department will use in-house, so will be fine. However, using the shipped defaults or following step by step instructions can be problematic as it is easy for one major check-box to be missed which can cause delays in the art department: the Marks and Bleeds dialog of the PDF export window.

The exports which ship with Adobe InDesign all have a crop offset of 2.117mm as default, (as shown above) which is not a lot. In the example above, none of the marks and bleeds have been turned on either, nor have the bleeds been set, yet this is how the defaults shipped with InDesign will appear.

It is not uncommon for a printer to ask a customer to submit a PDF with crop-marks on, but if a customer is making a PDF based on default settings and then changing the default values by simply clicking marks on or off without changing the offset values, then problems can occur later.

The issue comes about because crop marks which are too close either have to be removed on the PDF itself, or if the problem marks are left and and printed, may appear on the finished printed artwork. The position of the print cannot be guaranteed to be consistent on every sheet of paper (especially on digitally printed artwork) so variations in image position occur, so while the guillotine will be precise, the position of the crop marks from one sheet to another may not.

The example above shows the PDF file on the left created with only 1mm offset while Crop Marks, Bleed Marks, Registration Marks and Colour Bars are turned on. The result on the right is due to trimming innacuracy using the above PDF.

This doesn’t look like much of an issue on a DL flyer, but the consequences on a 400 page book would be much greater given the variations which can arise not just from the printing but also the folding, binding and then trimming.

To resolve the issue when native files were not supplied, printers will adopt the following options:

  1. Ask the customer to resupply the PDF with greater crop offsets;
  2. Leave the crops where they were and produce results similar to the one in the example;
  3. Delete the marks using tools in Adobe Acrobat Professional, hoping that none of the actual art in the file is deleted as a consequence; or
  4. Delete the marks using third party tools in Adobe Acrobat Professional such as Enfocus Pitstop Professional, which has more advanced selection and removal tools… but once again hope that none of the actual art in the file is deleted as a consequence.

If a printer chooses to adopt options 3 or 4, these are chargeable options which may harm the integrity of the file supplied to the printer as it has now been edited.

My own work recommends the applying Crop Marks and Page information only, having crop offsets of 5mm, and having bleeds of 5mm all around. This is illustrated in the image below.

Durable and Practical?

Artwork has to do more than just look good on screen. Make sure to speak to the printing company’s representative and ask questions about the durability of what is being printed, such as:

  • will the design get scratched or scuffed easily?
  • will the ink run or smudge under any circumstances?
  • is the ink colourfast or will it fade in sunlight?
  • will the artwork be able to be printed through a laser or inkjet printer?
  • is the paper stock appropriate for its purpose?
  • is the paper translucent or opaque? this is important when designing schoolbooks, as once pages are written on and turned over, the ink of the print or the customer’s handwriting can be seen.
  • will this binding method be appropriate for it’s use? tradespeople prefer to have textbooks which are lie-flat binds, so that when they open the book for reference the pages will not move or close shut
  • has a working prototype been made of the product? This is important for packaging or POS products.

There are other several practical issues which affect most cartons, envelopes or POS printed matter. A few examples are:

  • can the barcode be read easily by supermarket scanners?
  • will envelopes hold the matter they were designed to hold?
  • will the postal service reject the envelopes because there is ink in a particular area or in a particular colour?
  • does a label meet the required the appropriate labelling laws, particularly for food; censored works such as movies; or pharmaceuticals?
  • will the items fit into cartons easily?
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