Ligatures: Is This Trip Really Necessary?

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It’s normally taken as an article of faith that you should use ligatures in text whenever you can. Like most articles of faith, though, this one too comes with an asterisk. In practice, the importance of ligatures is measured on a sliding scale from mandatory down to undesirable.

Ligatures—those fused combinations of characters that set as a single glyph—have been around since type was first set. In the fonts Gutenberg used for his famous Bibles, there were over 200 of them, used both to make justification easier and to better imitate the writing styles of contemporary scribes.

Forty years later, when Aldus Manutius developed his first italic fonts (which saved space, hence paper, hence money), they contained over 60 ligatures. In Aldus’s case, though, the driving factor was coping with the numerous kerns necessitated in setting his italics.

Creating kerning metal type was a hassle. The kerns themselves had to hang over the character blocks next to them, leaning on them for support, as shown in Figure 1. Kerns were fragile and had a tendency to snap off. There was also the problem of overlapping kerns, where one collided with another. The best way out was to cast two or more characters on the same block.

Figure 1: This photo of a well worn piece of 18-point foundry type clearly shows the R’s kerning tail, which extends beyond the type block itself. This allowed the R to overlap the block next to it, drawing the two character images closer together.

When two such characters are attached to each other—ligated—this composite entity is called a ligature. When two (or more) characters are set as a unit but appear in print as separate, unattached images, the unit has historically been called a logotype.

Figure 2 is a view from within a font editing program, showing how kerns in digital fonts overlap the bounding boxes (the modern equivalent of printing blocks) of adjoining characters. Electronic fonts eliminate the mechanical problem of physical collisions, but they can’t resolve the problems of overlapping of certain character images.

Figure 2: The bounding boxes visible here (with baselines shown) demarcate the nominal boundaries of each character. In the Palatino Italic sample on top, the f has kerning features at both right and left, whereas the y only has a kern on the left. Both overlap the bounding box of the a.

In the Palatino Roman sample below it, the kerning hook of the f overlaps the bounding box of the l to its right and overlaps the image of the l as well. This calls for a spacing adjustment or the substitution of a ligature. Note that the tail of the y slightly overreaches the bottom of its bounding box. Long ascenders or descenders may become kerning features as well.

Today, we’ve been reduced to a rump set of ligatures that address the few remaining intractable spacing problems arising from kerning characters. These include the fl and fi combinations, and sometimes ff, ffi, and ffl as well. The culprit here is the hook of the f. (There are also some historical ligatures available—for example ct and st—but they’re used for effect, not from necessity). You can have your page layout program automatically substitute ligatures as available. In InDesign you do this by selecting Ligatures from the Character palette menu. In QuarkXPress, open the Character dialog box from the Style menu and click to Enable Ligatures.

In fact, though, ligatures are not always necessary. The reason that all fonts today include ligatures is not that all typefaces make them necessary, but that when character sets started to become standardized in the early 20th century, fonts tended to include ligatures whether they were needed or not. Printers expected them, so they got them. This habit has been carried forward in digital fonts.

During that same time period, though, there was a design movement afoot to design kern-free typefaces. Many of these are still available, as are faces derived from them or influenced by them. The kerning j was an early casualty of this trend (see Figure 3), but the key development here was the non-kerning f, whose hook stayed in its own back yard and didn’t hang over the fence into the neighbor’s property. Some examples are shown in Figure 4.

Figure 3: The kerning j didn’t create a need for ligatures because there are practically no circumstances in which it can collide with an adjoining character. But in the days of metal type, it still meant a fragile casting and resulting breakage problems. The non-kerning j remains a feature of many digital typefaces.

Figure 4: Non-kerning fs came into vogue in the early 20th century. To today’s eyes these characters look rather squashed, like a boxer with a flattened nose. In some cases, the non-kerning fs were only used at select point sizes, such as the Monotype Caslon 37 sample here, where it only appeared in the 18-point font.

The non-kerning f had practical advantages but was aesthetically challenged. It just wasn’t what people were used to seeing. As the 20th century advanced, a hybrid form evolved: what could be called the “nearly non-kerning f.” Figure 5 shows some notable examples. In metal type, reducing the size of the kerns made them more durable.

Figure 5: Reducing the reach of kerning fs reduces kerning problems while still allowing them to have natural proportions. Some classic 20th-century faces display this trait.

The issue of fragile kerns was of principal concern to printers using foundry type (hard, reusable metal type) and type created on Monotype machines (made of a softer alloy and melted down after a single use to create new type) which were cast on individual blocks, like the type in Figure 1. At the same time, linecasting machines (such as the Linotype, which cast entire lines of type as a single slug) had to use ligatures—specifically fi, fl, ff, ffi, and ffl—because these machines could not support kerning characters. Figure 6 shows the difference between Monotype’s Times New Roman of the period compared to Linotype’s version, simply called Times Roman.

Figure 6: The Monotype Times sample on top clearly shows kerning characters including the f and j. The Linotype linecasting version below it features non-kerning versions of these characters. At the bottom, the digitized version of the Linotype face has restored the f and j to their kerning forms.

This all means that in today’s vast digital type library—which contains many copies of old linecaster faces—you’re apt to find all kinds of designs that may or may not demand the use of ligatures.

Figure 7 shows a sample setting that looks perfectly fine without recourse to ligatures. If your h&j settings don’t allow much compression of character spaces, your type may likewise set perfectly well without resorting to ligatures.

Figure 7: In normal text settings it’s often unnecessary to use ligatures when setting with certain faces, for example the Stempel Garamond used here. In fact, in cases where ffl and ffi ligatures are unavailable, it may well look better not to use any at all.

An obvious concern when using ligatures is that they fix the space between the characters they represent, so as spacing gets looser, ligatures can stand out as tight spots in the type. Fortunately, most page layout programs will automatically remove ligatures in favor of their constituent characters when spacing becomes looser, as when justifying type or opening tracking.

This is a good thing, but it’s not a perfect system. First, it only works when the ligatures have been placed automatically by the program. If you insert them manually, the program will not disassemble them for you. Secondly, programs may remove the ligatures before the spacing has become loose enough to make them unnecessary, as shown in Figure 8. A third issue is consistency: having ligatures come and go in a single text is undesirable. These are the kinds of small stumbling blocks to reading that the eye catches with alarming ease.

Figure 8: Here the process of justification has caused enough character-space spreading to trigger the elimination of ligatures in the second line. Unfortunately, the character spreading is not great enough to eliminate the unsightly character collisions that ligatures were created to eliminate. In cases like this, ligatures should be reinserted manually.

Then there’s the question of ligatures in sans serif type. Most sans serif fonts don’t include true ligatures, although they do include (as part of the standard character set) multiple characters included as single glyphs. These compound characters are actually logotypes (although no program ever refers to them as such), as seen in Figure 9. Logotypes usually look no different than the same characters set separately, and the spacing of their components is the same as that of the default spacing built into the font. But this doesn’t make them unuseful—in some sans serif faces, using logotypes has the effect of preventing near collisions from appearing in crowded settings; in essence, these act as anti-ligatures. Before using a sans serif face, it’s worth looking into what its ligatures look like and how they work.

Figure 9: This selection of common faces shows the various kinds of sans serif ligatures available. In each pair, the upper example is set with ligatures, the lower without. In the Futura sample, the two settings are identical; the ligatures set exactly like the individual characters. Myriad, by contrast, includes true fused ligatures. Gill Sans has a distinctive form for its fl ligature, but its main role is to separate characters, not to join them, as the ligature-free lower sample reveals.

Personally, I don’t care for the appearance of true ligatures in sans serif type. To my eye, they disturb the clean geometry and consistent texture that give sans serif faces much of their appeal. But that’s just me.

As Figure 7 illustrates, when you need them, having a full set of f, l, and i ligatures is better than having just the fl and fi versions that come in standard fonts. Again, it’s a question of consistency and continuity of texture. In general, ligatures are more important when using faces with longer historical pedigrees. Those based on the work of such seminal figures as Garamond, Janson, and Caslon, for example, will tend to have more—and more exaggerated—kerning characters that need special attention, particularly that looping f hook.

But where spacing is wide—in online or e-book type, for example—or where typefaces have been designed to minimize the impact of kerning characters, using ligatures often becomes optional and may even become a nuisance. In conclusion, then, it’s safe to say, “Ligatures: yes, but....”

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