As a prepress operator, one of the first checks that I undertake on client submitted artwork is a spread-by-spread check to see how design elements using the black separation behave – particularly if it is overprinting or knocking out. This is done by viewing a spread in Adobe Acrobat, and toggling the black separation on and off from the output preview panel. I’m checking to make sure that any lines, fine type and small type that have been coloured 100% black exhibit an overprint behaviour. I’m also checking that larger areas of black, such as large heavy fonts or large areas of black set as vectors are either knocking and/or have a rich black colour applied to them.

Usually, artwork that has been set up with Adobe InDesign will have the black overprints behaving as expected. I might have to change the odd large rectangle of black to a rich black, but that is because InDesign has a preference – that is on by default – that any 100% tint of [Black] – should overprint.

Most other layout and drawing applications do not have this feature, and not all PDFs submitted for printing come from InDesign (e.g. Illustrator, Canva, Affinity Publisher), so this is one of the first checks that I do.

But in recent years, I’ve noticed a growing trend to set text – regardless of its point size or weight – to a tint of black rather than a solid black. One of the ways I first noticed this was while doing my ‘black overprint sweep’ and seeing large areas of white text knocking out of a coloured tint when the black separation was off, and once the black separation was on, noticing that the type appeared to be black… but instead of being 100% black, was a 90% tint of black.

In fairness, this isn’t an issue of major concern if the tint is applied to fonts that are:

• thicker than the regular font family e.g. bold, black, etc.
• large in size e.g. 36pt;
• on its own and not touching any adjacent colors; and
• it is used sparingly e.g. not used as body copy but used in something like a pull-quote

Why could this present a problem?

We’re not printing in grey

To achieve the 90% tint (what a designer may see on-screen as a ‘dark grey’) we’re not actually printing a pre-mixed dark grey spot colour – we’re printing black that has halftone dot through it. Here is what a 90% tint of type looks like up close.

Looking at this type up close, it looks like what should be sharp type but has halftone holes through it here and there. If anything, it almost looks broken.

Press operators may try and compensate for it

The next issue is that the press operator may see this phenomenon on press, believe it is meant to be a solid fill without the halftone holes, and to accomplish this will put more black ink onto the press. This will fill in the halftone holes, but will also darken everything else on the page.

It doesn’t lend itself to trapping

Perhaps the press operator is familiar with what the designer is trying to achieve and doesn’t ‘run up the black’ but runs everything to appropriate densities. This might be fine if the tinted type is in its own area of white space, but when it is printing over the top of another color, then issues will occur with trapping.

If you’re not familiar with this term, trapping is the adjustment of artwork to compensate for ink misregistration during printing by making adjacent objects slightly overlap so that an object with a lighter colour will spread under an object with a darker colour; or an object with a dark fill (such as a rich black or a double-hit of an ink) may choke the inks that do not make the shape.

Using the last figure as an example, here is how the lettering would look on a tinted background once trapped. I’ve made the black lighter in this illustration to demonstrate the trapping, particularly how the cyan has spread underneath the black to the point where it has nearly filled in.

That said, black tinted type over a lighter coloured background will need to be trapped in order to compensate for any ink misregistration. Because black is usually the darkest ink, it means that the lighter coloured background will have to spread. However, when this is done on a thin type, it is often to the point where any white show-through to display the ‘gray’ is often lost.

What can be done?

• Don’t black-tint fonts that are less than the ‘regular’ font family (e.g. light, ultra light, thin, ultra thin) or below a certain point size.
• If you insist on using black-tints with thinner than recommended fonts, at least consider applying an overprint property to this type either manually via the attributes panel, or when performing a preflight check in Acrobat using preflight fixups (or if you have access to it, Enfocus Pitstop Professional).

Ultimately the key point I’d like readers to take away from this article is be careful making small, thin type either a tint of black; or making it white over a colourful background.

In terms of when a black should be set to knockout or overprint, this is dealt with in a couple of previous Colecandoo articles that cover the issue in greater depth and are worth a read. The links to those articles are here and here.

As an aside – applying process colours to thin type

This post has mainly been focussed on avoiding the use of black tints with thin type or over lighter coloured backgrounds, but the same consideration should also be given when applying colours that are made of several process colours.

Take the following green examples that are made from a mix of all four process inks.

Note how the light and small fonts are barely legible. This is also assuming that the inks are in perfect registration. To see what the image looks like with misregistration, use the slider in the middle of the image.

Not only are the light and small fonts worse, but other styles that were previously legible are now bordering on illegible.

If you’re then considering “but my offset print supplier’s prints are always in registration” or “I use a colour laser printer so my prints are always in registration”, don’t be so sure – printing and registration tolerances are just that: tolerances (read this previous article for more).