Intolerant about tolerances

Designing print projects on-screen comes with a false sense of precision. It is easy to assume that whatever is designed on-screen will accurately reproduce – without flaws – into a real-world finished product. This is reinforced by the ability to place objects on precise coordinates and align and distribute with similar precision.

Unfortunately, the practical application of the design from computer to real world product comes with a series of tolerances that are not taken into account in the design software.

Such examples are

  • Variables in the substrate. Paper stocks can stretch, distort and swell based on humidity, storage conditions, temperature and ink density, just to name some variables.
  • Creep (aka shingling, pushout or thrust). This is covered in an earlier article, but it is the phenomenon of artwork in a book moving towards the foredges of pages due to the gathering of folded sections.
  • Registration between inks and Embellishments.
  • Precision of the paper folding.
  • What your computer says vs what the output device prepares.

Some tolerances are hardly noticeable and imperceptible without magnification, while other tolerances are large in comparison. This article will examine several print phenomenon and the tolerances associated with each phenomenon.

Tolerances in ink registration

This is an example where tolerances are quite tight, and best shown when printing several colours in one pass, such as full colour process offset printing, digital toner or inkjet printing. Take for example the following headline.

At normal magnification, the inks appear to be in perfect registration. However, when zoomed in, it is possible to see that the registration of the inks is slightly off, demonstrating tolerances in microns.

However, it doesn’t take much to make the tolerances worse, such as:

  • Using a printing method where misregistration is a larger concern, such as flexography or screen printing;
  • Printing additional colours on a second pass, meaning the sheets have to dry first and add the variable of paper distortion to trying to register the additional inks to the previously printed inks.

Embellishment registration

From here, tolerances begin to get worse. Take for example a full colour plus one spot colour print that has an additional spot UV clear varnish applied over the lettering.

Note that while the inks are in register, the spot UV is off by half a millimetre to the top right. This is because two separate processes were used – a five colour press to print the inks onto the paper; then the spot UV was applied using a screen printed stencil that was made using an imagesetter that was different to the platesetter that produced the images for the plates.

Another example is how a design translates from screen to embellishment. Take this complicated foil, and notice how the fine detail in the foil is lost.

Fold registration

This is where tolerances can be out by several millimetres. A simple exercise that demonstrates this issue is to take a sheet of paper and fold it in half four times, then look at how the pages line up at the heads and feet of the folded pages. The same issue occurs when taking an imposed sheet and folding it into a signature to combine with other gathered signatures for burst binding.

Take the following example that has a running header in InDesign where the sidebars bleed off of the foredge. Note the difference between the highest point vs the lowest point.

What can be done?

  • Know that printing and binding are not precise and subject to tolerances like any other manufacturing. What is important to know is where the extreme tolerances lie and how to design with them in mind.
  • Speak to your printer or finisher and ask to see samples of previous work.

There is also page to page registration that needs to be discussed, but this will be covered in a future Colecandoo article.

Consistent spot color naming to die-forme

A pain-point I see regularly concerns inconsistencies in color names, particularly spot colors that are used for embellishments. Take for example a color that is used for representing a forme-shape. For consistency sake, the office has implemented a CC library with standard swatches for regularly used embellishments such as Dieline, Perforation and Spot UV. The concept is that anyone who requires an embellishment can simply open the CC library and choose one from the embellishment colors that have been established.

Despite creating this CC library, embellishment colors and names can still be inconsistent for reasons such as:

  • The artwork was legacy artwork prior to introducing the CC library;
  • Operator error; or
  • Art was supplied by a third party, such as a client or supplier.

Naming consistency is important with workflows that have been established with these embellishment colors. Take the color “Dieline” for example. This should be clearly visible on the native files, but not on the printed output. In this instance when printing to digital devices, the RIP will identify the color “Dieline” and assign it a white color value that will treat it as if it were transparent and not print at all, though it will appear in the PDF. This eliminates the need to toggle a dieline layer on and off in the application that made the artwork, and eliminates any errors associated with art being mapped to incorrect layers.

However, if the artwork contained a color named as “Dieforme” for example, the RIP would not identify the color as “Dieline” and the formeshape would be visible on the final print. This issue could be resolved by adding the color “Dieforme” manually to on the RIP, but the concept is to have every file the same so that operators aren’t interrupted having to make adjustments on the RIP for specific tasks.

A solution via Acrobat

My preferred solution is to use a custom fixup from Adobe Acrobat’s Preflight dialog. In this example, I’ve created a PDF that contains ten variations of Dieline spot color using different names, but the color value is identical. Here is what the separation preview looks like:

Acrobat does have pre-made fixups for similar tasks, such as Make custom spot color names consistent.

Let’s give that a go.

The fix has reduced the number of spot colors but only down to five. Names that had different casing have been merged together, and spaces or dashes have been removed and then merged together with the results.

Let’s revert that and try an alternative fixup Merge spot color name if appearance is identical.

OK, that has remapped all of these spots to one spot color.

However, this color is the wrong name. It is also unlikely that the forme-shape colors would ever be set with different names yet have the same underlying CMYK color conversion. The following would be more likely:

Let’s run the Merge spot color name if appearance is identical fixup again.

Some names have been culled but there similar names such as die and Die have not been mapped together, so this solution hasn’t worked.

Make a custom fixup in the Preflight panel

Luckily we can make our own solution from the Preflight panel by clicking on the options button at the top right of the panel and selecting Create Fixup

In the new window, the fix will be given the name Diecut Fix. Choose Color spaces, spot colors, inks from the Fixup category in the top centre dialog; and select Map spot and process colors in the Type of fixup dialog on the top right hand side.

In the options at the bottom of that dialog box, make sure the Source color name matches with RegEx and in the field to the right, type the GREP ^die.*?$ – this will look for any word that begins with die. The destination should Map or rename, and the destination color name will be Dieline, with a CMYK value of 100% magenta, overprint on, and applied to Spot color is used. The checkbox should be checked on for ignore upper/lower case. Once OK’d from the bottom right hand corner, the fixup can then be activated using the Fix button on the bottom right of the Prepress dialog.

The fixup has worked – all of the colours have been mapped to the one color with the correct name and color value. An added bonus is that the color is set to overprint so that the color beneath won’t knock out.

Other applications

In this instance, the fixup has been used to fix a one-off issue concerning an incorrectly named spot color. But this fixup can be added to a larger workflow so that artwork from external sources can be cleansed for a workflow. See this article for more information (https://colecandoo.com/2019/02/24/droplet-like-its-hot/)

This particular fixup is also used to fix artwork that – while being set in the right color and name – did not have an overprint applied to the color. This fixup will correct this issue.

Add a “Night” mode to InDesign

In the same way that different political or religious views can polarise a group of people, so can one specific InDesign feature: Light or Dark interface.

Introduced into InDesign CC in 2013, this change brought InDesign in line with other Creative Cloud products that had a dark interface. That said, I was not a fan and chose to remain a user of the light interface.

Many years later and Apple released the macOS Mojave with its Dynamic Desktop and Dark mode. The Dynamic Desktop feature shows a bright desktop during daylight hours and a dark desktop during the dark hours. In addition, popular apps also followed suit allowing users to switch from the usual view to a “night mode”.

In addition, I have found myself working late into the night on projects, and have found that a darker interface during these hours is easier on my eyes. That said, I still like to use a light interface when working in daylight hours.

With this in mind, I wondered if it was possible to create an InDesign startup script that – upon performing a common task such as opening a file – would check the time of day and if it was beyond a certain time of the day, would invoke the dark interface… and it was.

I’ve now added this script to the site and it can be downloaded from here or the scripts/download pages. As this is a startup script, it has to be added to the Startup Scripts folder (see Ole Kvern’s excellent instructions for doing so here).

The script can also be modified to suit by going into any text editor such as textedit or notepad and editing the following lines of the script:

if (hours <= 7 || hours >= 18)

This indicates the hours of the day. In the script, 7 = 7:00 am, and 18 = 6:00 pm.

app.generalPreferences.uiBrightnessPreference = 0.0;

This refers to how dark the interface should be. 0.0 is totally dark, 1.0 is bright, but values from 0.1-0.9 can be used as well.

app.generalPreferences.pasteboardColorPreference = 1; 

This refers to the color of the pasteboard. The number 1 will match the pasteboard color to the interface, whereas 0 will leave the pasteboard white.

So technically it’s not a night-mode per se, but for those who like the light interface until the night-time hours, this script may be something to consider.

Housekeeping Scripts

You finally have an approval on that print project you’ve been working on for the last few months. All that’s left to do is make a PDF for the printer and be done with it, right?

Nope. It’s time to do some housekeeping on the file. Let me use this metaphor, once you’ve made dinner, you don’t leave your dirty pots and pans in the sink, do you?

It’s time to do some housekeeping, and in this episode of “must haves” on the Colecandoo Youtube channel, we’ll look at several scripts to keep your files nice and tidy.

Disclaimer

One word of caution with any of the scripts shown in the video. They are all destructive in nature. That is, they intentionally remove items from a document. Make sure you save your work prior to running these scripts, just in case they have a catastrophic impact on your artwork. I’m showing these scripts for educational purposes only, this is not a tutorial on how to use these scripts.

Images and Frames

Cleanup Pasteboard

The first script removes items from the pasteboard. Run the script and select the distance from the trim edge and importantly whether threaded text on the pasteboard should be removed.

I can hear some of you now saying “but what if I’ve left important notes on the pasteboard for the next person who works on the artwork”? Well, either don’t use this script, or put your notes on after you’ve run this script.

Empty Frame Remover

This script removes any purely empty frames, that is no fill or stroke that have no special settings applied such as text wrap or text on a path. Once run, it scans the document and removes all of these empty frames.

Trista DPI

The next script resamples all images over a given resolution to a more appropriate resolution. It’s great for projects such as yearbooks where the resolution of images is often far greater than it needs to be.

Now, I was in two minds to whether I show this script or not. Out of the scripts being shown in this video, this is both the most powerful and potentially most destructive of them. Ultimately, read the instructions before using this script, and make sure you have access to backups in case things go wrong.

Colour

Next, let’s address some colour issues that may have come about from selecting registration by mistake, or left-over swatches from a Microsoft Word import.

Unlike many scripts I’ve shown previously, most of these scripts are buried in forum posts, so it’s a matter of reading the post, finding the script, copying and pasting into a text editor and saving as a .jsx file.

It’s worth noting that all of these scripts only affect colours generated within InDesign, so won’t fix colour issues in links such as PDFs or photoshop files.

Add unnamed colours

Let’s start off with this easy one-line script that adds all unnamed colours to the swatches palette. True, it’s just as easy to select this from the swatches menu. Regardless how it’s run, this should be the first step to cleaning up the swatches. You can cut and paste it from below:

app.menuActions.item("$ID/Add All Unnamed Colors").invoke();

Reduce Colors

This script launches a prompt that allows you to search for colours that are a given percentage different from each other and merge them to the swatch that appears higher in the swatches panel.

If you’re using a special knockout black swatch and don’t want it to become the default black, perhaps make it a spot colour while running these scripts.

I explain the differences between these colours in more depth in Episode 14.

Registration Fix

This script converts all registration colour applied by InDesign to its respective tint of Black.

RGB/LAB GREY swatches to Shades of Black

I’ve written a script that converts RGB and LAB values that appear as shades of grey to equivalent shades of Black, while leaving other swatches alone to be dealt with by another script.

RGB/LAB swatches to CMYK

There’s another RGB/LAB converter, though this script converts all RGB/LAB swatches to CMYK values.

Faux Black fixers

There are two scripts that can take faux black values and convert them either to 100% black or rich black. The faux black is determined by CMYK values beyond certain percentages. In this case, any swatch that is over 70 Cyan, 60 Magenta, 60 Yellow and 90 Black will be converted to either 100% black or rich black. You can dig into the script if you like, and redefine what constitutes a rich black or faux black.

Remove unused swatches

This will remove any swatches not used in the artwork.

Styles, Master Pages and Layers

Let’s make sure that we only have the necessary styles, master pages and layers that are required for the artwork.

Remove unused masters

This script removes any master pages that have not been used in the artwork.

Remove unused layers

Next is this script that removes any layers that contain no artwork.

Remove unused styles and groups

This is a series of scripts that removes any styles not used in the artwork, as well as unnecessary style groups that may have been left, whether deep in folders or not. In the video it is combined into one “catch-all” script for convenience, but it is the work of many authors, so it’s not right for me to host it. Links to the originals can be found here, here, here, here and here.

Delete guides

Lastly, this script removes all guidelines in a document. I can see that there would be some use for guidelines to remain in a document, but felt it was worth demonstrating.

Preflight

To be sure that the artwork is completely free of issues, we want to make sure that there are no prepress issues. To make sure that the artist complied with the preflight that was associated with the document, there’s the preflight enforcer.

As shown on the Colecandoo Youtube channel before, I’ve prepared two scripts that will either warn or prevent a user from printing or exporting to PDF until all preflight issues are resolved.

So there you have it, over ten scripts that will help make housekeeping of InDesign files a lot easier. If there’s any that I’ve missed or you feel would be worthy of a future video, let me know via my contact page.

Preparation for Color Separation

In recent times, I have received several pieces of “finished art” supplied by clients where the sales representative has informed me that the printed material must be “on-brand” according to the client’s style guides. That should be the end of the story, but upon checking the finished art, it is clear that the artwork has not met the client’s own style guides, or been thoroughly checked by the client prior to submission.

One of two things will now happen – the prepress department can either fix the artwork without disturbing the client in order to fulfil the brief and expedite the work, or we can contact the client informing them of the situation and THEN ask whether we can fix it or have resupplied artwork that is color correct. Considering that the client may receive their proof and resupply the artwork in its entirety, this means fixing the colors again.

For years, I’ve been an advocate of receiving finished artwork that is correct for the following reasons:

  • The client has correct content;
  • Eliminates the risk of human error in prepress from incorrect or unintentional manipulations during corrections;
  • Prepress can output more work considering they are not spending time manipulating files that may only be replaced at a moment’s notice;
  • My employer isn’t losing revenue on prepress time that usually is not passed onto clients by the sales representatives.

That said, I make sure to contact customers who have supplied finished art that is incorrect and outline the issue, giving them the opportunity to resolve the issue themselves or let us do it. It is at this stage where some customers have been willing to fix the artwork themselves, but cannot see the issue. When I ask them to check the separations preview panel, the answer is always the same – “where’s that?”. Because this is a panel that I use so often as a prepress operator, I often think to myself “are you kidding me?” but to be fair, there are many panels in InDesign that I don’t use such as the animations panel; and I would have no idea how to use either.

On that note, I have prepared a video on my Youtube channel on how to use the Separations Preview within Adobe InDesign and used it to highlight instances of color mismatches, issues with black ink, and when white overprints.

This is not the first time I’ve been on my soapbox about this before – (see this article). It also directly relates to:

I’m gonna knock you out, my printer didn’t knock you out…

An earlier post “To Overprint or not to Overprint, Black is the question” explains how the colour labelled [Black] in InDesign behaves, and when solid black ink should and should not knock out of the colours behind it.

Paying attention to this advice and applying it to artwork should result in a good printed reproduction, correct? While the answer should be yes, there is one more level of control of black appearance and overprints, and that is in the hands of the printing company and their output software.

OFFSET EXAMPLE

Let us look at this following example:

ko1

This card is set up for a Black plus spot output for an offset press. The Black is only overprinting on the text as misregistration would be noticeable here, but the Black elsewhere is knocking out so that the colour does not look muted through the yellow.

However, despite best intentions and checking the separations both in InDesign and Acrobat, the card has printed like this (effect is exaggerated for the screen):

ko2

So what has happened? The separations were correct, they were checked in both InDesign and Acrobat! It turns out that the Raster Image Processor (RIP) software that the commercial printer uses to image the design onto the printing plates has its own settings. Here are some example screenshots from AGFA’s Apogee X system and Fuji’s XMF system respectively about the overprinting of black:

apogee

xmf

In both screenshots above, the respective RIP software CAN honor the settings that were in the initial PDF and not apply its own preferences, but in the instance of the business card, the RIP settings overrode the PDF settings and chose to overprint all instances of 100% black, regardless what swatches were chosen in InDesign.

DIGITAL PRINT EXAMPLE

Using the same artwork, the card was printed via a colour copier, but this time the result was as follows:

ko3

So what happened here? The while the solid black looks good, where the black in the top line meets the vignette looks rather weak, and there are is a lighter black around the travel agent. What is going on?

Again, the RIP software has manipulated the artwork with unintentional results. Unlike printing directly to a desktop printer, most digital printers will print to a RIP where the file can be imposed, colour adjusted and printed in whatever order the prepress operator sees fit.

Using the EFI Fiery RIP, there is a little-known feature of the RIP that changes the way black is displayed that can produce unexpected results, and that is in the color settings dialog box and it is “Pure Black On”.

Screen Shot 2013-06-03 at 2.55.28 PM

This setting takes every instance of 100K and ramps the colour to a “super black” as opposed to using the black toner only. Again, this setting can be changed, but when this card was printed, the defaults were unchanged resulting in this unwanted appearance.

This setting only applies to vectors and text AFTER the PDF is flattened into postscript. This is visible where the rich black abruptly changes to the muted black. One look at the flattener preview in InDesign confirms that areas of flat black in that image were as a result of the flattening.

ko4

THE RESULT?

This small example shows how changing the client’s intended black overprints can have unwanted consequences. For prepress operators it is a wake-up call to make sure that the RIP defaults will maintain the clients’ expected results; and for designers or publishers it is worth understanding that even the treatment of black overprint is an important topic.

You’ve gotta keep ‘em separated – check colour separations!

There is absolutely no doubt that submitting finished artwork as PDFs has eliminated several prepress issues such as missing links and (mostly) missing fonts. Sadly, it has not eliminated all prepress issues associated with submitting artwork. In this post, I would like to look in more detail at an issue which is to me a fundamental step before submitting finished artwork, and that is checking colour separations in a PDF – properly! Not doing so is a cardinal sin of prepress.

For this, I have created a mock-up black and two spot colour flyer for a favourite destination of mine, Montréal. On face value, the PDF appears to be fine, but after looking at the artwork in more detail such as the crop-marks and where the artwork bleeds, it is clear that the bleeds will need to be fixed.

This is issue one. The rest is fine, right?

No! To see the other issues, the output preview dialog box has to be open. To get there using Acrobat 9, go to the advanced tab, then print production… , then output preview

Suddenly, the preview changes a little. From here, it is possible to see checkboxes for both process plates and spot plates. This job is Black plus two spot colours, so all appears to be right so far… but what happens when the black channel is turned off?

Instead of disappearing, the black becomes lighter. This means that the black is not purely on the black separation, but rather all of the process separations. It should look like this:

So what is going on here? It would appear that the blacks are actually made of process despite appearing greyscale, the photograph may have been RGB or CMYK. The type, despite appearing black, may be made using RGB black. So how can this be determined?

In the output preview dialog box, there is a dropdown which says “Show”. By default, the dropdown result is All, and this means that all gamuts on screen are shown, but not necessarily what images are process, spot, RGB or LAB.

If the dropdown field is changed for example to RGB, it is possible to see what items on the page are RGB only.

After doing this, it appears that the type on the page is RGB which is why it isn’t colour separating properly into black. This means going back into InDesign and changing the RGB black to 100% Black. OK, one issue, but what about the masthead picture – that isn’t RGB. It is possibly made of a “faux black” out of process, so the dropdown needs to be changed from RGB to CMYK.

I can now see two things: what appears to be a black and white picture, and coloured type in the left middle of the page. To determine if the black and white picture is actually on the black separation only, the black separation has to be toggled off.

The image has become lighter, but not disappeared. This tells me that the image is made out of process instead of being greyscale. This means going into photoshop, making the colour mode greyscale, resaving, relinking in InDesign. That is two issues.

But why was there process coloured type? It should be two spot colour separations plus black. To check this, change the dropdown field to spot colour.

Now I can see the word Montréal in solid 494, the background in a tint of 494, and the strip of yellow 610. But the words “WHEN SHOULD I GO?” have disappeared. This infers that these items were not made out of spot colour, or they should be visible in this view. Instead, the items must be made out of process, as they were visible in the CMYK view, but not Spot Colour nor RGB views.

So after checking the PDF and its separations more thoroughly, I now know there are several fixes required for this PDF: The InDesign file needs to have the following changes:

  • Colour which extends past a trim area has to bleed off;
  • The RGB black type needs to be 100% black only;
  • The “black” photo of Montréal needs to be made greyscale;
  • The words “WHEN SHOULD I GO?” and yellow strip behind need to be changed from process to their appropriate spot colours.

I have prepared before and after PDFs for the purposes of trying what has appeared on this post.

Spot “color” of bother

Why converting spot colour to process on process artwork is not such a good idea.

Ever had a supplier make contact to say that there are spot colours in the artwork supplied, and wondered “Why don’t they just convert it and leave me alone? Why are you bothering me with such a simple thing?”

1) Possible breakdown in communication

For the art department of the supplier, this will normally be the first time that they have seen the artwork and be totally unaware of its history or construction. All the art department will normally be concerned with is that the details on the docket match the artwork, and that the artwork meets the mechanical specifications for the press, such as correct colours, bleeds, page size, etc.

For a prepress operator, observing a spot colour in addition to process artwork raises red flags such as:

  • Is the artwork actually meant to be CMYK+spot?
  • Is the artwork meant to be all spot colour?

Similarly, if a prepress operator receives artwork with instructions that the artwork is to print in Pantone Red 032 for example, but the file is prepared in Pantone Warm Red, the prepress operator will ask the question: is the colour being printed on the docket correct, or is the ink in the customer’s artwork correct? This is not uncommon problem in a printing business and is a great way of delaying proofs and creating confusion.

2) How the conversion is done

“Converting” a spot colour all depends on how the conversion to process is done. Take for example the color Pantone Red 032. Depending on which application made the PDF, the colour can appear with several breakdowns:

  • Adobe InDesign 5.0 (Pantone Solid Coated Library) – C0 M90 Y86 K0
  • Adobe InDesign 5.0 (Pantone Color Bridge Library) – C0 M90 Y60 K0
  • Quark Xpress 8.0 – Solid Coated Library OR Color Bridge (using the CMYK output) – C0 M90 Y60 K0
  • Quark Xpress 8.0 (using the CMYK and spot/As Is methods) – LAB colour

In addition to this, the printer’s RIP also has the ability to convert spot colours to process in a PDF based on the alternate value within the PDF, or a value based on a spot-to-LAB-to-CMYK conversion.

Furthermore, a customer’s corporate stylesheet may have several colours of a logo depending on the circumstance that the artwork is being used, such as:

  • if appearing in newsprint in process, use this breakdown;
  • if appearing on glossy stock in process, use this breakdown;
  • if appearing in newsprint in spot, use this spot colour;
  • if appearing on glossy stock in spot, use this spot colour;

3) If the PDF has transparencies, drop-shadows or the like.

If the PDF has been made to Acrobat 4 compatibility (1.3) and features drop shadows or any effects above a spot colour which was flattened once the PDF was made, then a spot to process conversion may not even be possible. Areas which were flattened will become white, as demonstrated in the illustration below.

4) The client’s expectations of spot v process

Some spot colours such as metallics, fluoroescences, pastels etc convert terribly to process, regardless of which method to convert them was used. If the client has chosen spot colours from a swatch book with no process equivalent next to the swatches, and expects these colours to reproduce out of process colours and look identical to the swatch book, then they are setting themselves up for failure.

Some swatch books (such as Pantone Color Bridge) does display its swatches with the spot colour on the left and how it appears converted to process on the right.

However, if a customer is shown a swatch using the book and it is not made clear between the difference in colour between spot and process, the customer will be disappointed once again.

The bottom line?

If artwork is to print process, prepare the artwork using process colours only. If the artwork is to print in spot colours, make sure that the spot colours in the document are going to be the same spot colours going to press. If your client has supplied you spot colour artwork which should be process, ask them to supply process artwork. If they complain and ask why, point them to this article.

The name is Preview… Separations Preview

Despite this magnificent feature being introduced since the first release of Creative Suite, I am still amazed at the amount of people who either don’t use this preview, or know it exists.

For those who don’t know what i’m talking about, Separations preview is a way of viewing the InDesign file so that it more closely resembles what it will look like once printed. It also lets users toggle through the ink separations which are available in the document.

Using separations preview it is possible to determine common prepress errors such as:

  • Unwanted overprints, such as white overprints suddenly disappearing from view;
  • Items set as either non-printing objects or non-printing layers (they will disappear completely from view);
  • Undesired black overprints, such as a solid black overprinting a photograph and still having the photograph visible instead of knocking out;
  • With the exception of photographs – real blacks instead of faux blacks (e.g. items meant to be 100% black only but instead composed of all four process colours);
  • Effects which won’t work with spot colours such as color burn, soft light or overlay (the areas over spot colours using these effects will dissappear);
  • The use of Registration colour (will appear on every single separation as a solid);
  • Any spot colours which shouldn’t be in the document – either because they aren’t actually in the design but are still in the swatches palette; or if they were meant to be converted to process using the ink manager;
  • Unwanted knockouts, such as a dieforme overlay which wasn’t set to overprint and has knocked out the artwork underneath it.

Similarly, Adobe Acrobat has a separations preview but goes some steps further such as:

  • How the artwork will appear based on different colour profiles; or to simulate black ink and paper appearance;
  • Can show whether the images in the PDF are CMYK or other colour spaces, such as LAB, RGB etc.

This is only using separations preview as well… haven’t even mentioned the Ink Limit view available in both Acrobat and InDesign; or the Flattener preview available in InDesign… but will save them for another post.

“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.

To Overprint or not to Overprint? Black is the Question!

To compensate for misregistration on a press, printers often ask that the colour black be set to overprint so that any misregistration cannot be seen.

However, black fills placed over coloured panels or scans which have overprinted can still be seen through the black ink. Overprinting black is recommended for lines under 2pt thick or type under 60pt, not necessarily for all black fills.

This is a particular concern in Adobe InDesign as by default, all solid 100K generated in the InDesign using the [Black] swatch (that is, not in graphics placed into InDesign) will overprint unless the default is changed in the preferences.

How to find the “appearance of black” options in Adobe InDesign. By turning OFF the checkbox highlighted in RED, all blacks made in Adobe InDesign will now knock-out. Also note how the black appears in this dialog box… all blacks are being displayed as Rich Blacks rather than Accurately which is a better option and should have been used for this example.

When placing black fills, consider what is underneath the black overprinted fill. If the job is CMYK, consideration may also be given to using a “rich black” which will give a dense black and prevent the black from overprinting, knocking out whatever is underneath the fill.

If a black DOES need to knock out while keeping all other blacks overprinting, it is possible to make another black swatch as only the default black (has square brackets around it e.g. [Black]) will overprint by default. e.g.

and so that it can be easily identified amongst all the other swatches which may be in the palette, how about an appropriate name such as “Knockout Black” for example?

Among printers, there is debate about what constitutes an ideal “rich black”. Some argue that it is 60% Cyan and 100% Black; others argue various percentages of Cyan, Magenta, Yellow and 100% Black; but for me the values 30% Cyan 30% Magenta 30% Yellow 100% Black has worked for me for years.

The following picture demonstrates various fills in an InDesign file.

The next picture illustrates what happens once the various fills are printed.

In this example, it is clear to see that “White Overprint” has simply disappeared. Beneath the Black Overprint, it is still possible to see the headlights of the traffic trails of the photograph underneath. While Registration does look almost like a super black, what can’t be simulated on-screen is the effect that solid registration has on paper, over-saturating it and making it distort. Other reasons not to use Registration Colour as a fill can be found in the Registration Colour post.

Considerations should also be made when using Blacks with Metallic inks, as Metallic inks are opaque and block out the inks beneath them, unlike normal inks which add to the colours beneath them. See the Metallic Inks post for more information.

Controlling black overprints is often best left in the hands of a prepress operator, but I do believe that forewarned is forearmed.

Metallic Inks

Unlike most inks, metallic inks are Opaque – that is, they are not transparent like process colours. Instead, they block out any other colours which printed before their run on the press, and are quite viscous and thick (have a low-tack rating) and take a long time to dry.

Before preparing artwork with metallic inks, please talk to your printer. This is because drop-shadows, black type/solids and objects/rasters over the top of metallic inks with effects such as multiply or darken may not print as they appear on screen.

Quite often to achieve the on-screen appearance, printers may use what is known as a “dry trap”, meaning the metallic ink will be printed in one pass, then left to dry, and once the ink is dry, the other colours are run in the next pass. This can also be done in reverse, but the end result is the same – two passes through the press, which not only takes longer, but means misregistration is more likely due to paper stretching as ink dries, and will cost more in press time.

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