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Mar - 2015
The complex task of the serif
→ What are serifs good for, why do some typefaces need them and others don't? This question addresses one of the fundamentals of type design, the function of the serif in the context of contrast. Understanding this issue is much easier when explaining it from the vantage point of calligraphy but for all of us non-calligraphers, here is an explanation that tackles it from a purely empirical perspective.
Looking closely at the transition of thick to thin, tracing the stroke of the bowl in a glyph like the lowercase b a characteristic dynamic in the development of thickness (or visual weight) can be observed. The difference in stroke weight and the transition between the thickest and the thinness moment is called the glyph’s contrast.
Different kinds of contrast
Take for instance a modern typeface like Bodoni or Didot (below on the left) where the hairline curls around with unchanged thickness and then suddenly picks up weight. This kind of contrast is called Expansion contrast. The term refers to the expansion of the pointed nib when the calligrapher applies pressure to the pen. When the nib expands the trace it leaves on the paper thickens.
Now compare this type of contrast to the gradual transition of weight in the b’s bowl of a humanist typeface like Arouet (above on the right) or Bembo. Starting at the very first moment where the bowl branches from the stem, the thickness of the stroke increases steadily throughout the arch until it reaches the top right of the bowl. The way thin turns into thick happens in a very typical manner: The inside contour of the bowl runs parallel (offset to the top and to the right) with the outside contour. This type of contrast is called Translation contrast.
Keeping this observation in mind check out the lowercase character i in each of the two typefaces. Without the serifs attached to that short little stem, the i might be part of just any old sans-serif typeface as there is no transition of visual weight. Without serifs the i would not have any contrast. The serifs take over this specific role. They represent for all the stems the transition of contrast that is taking place in the bowls. That way, with the help of the serifs, every stem in a typeface expresses the same thick-thin contrast as the bowls. This binds the glyphs of a typeface together. Thanks to the serifs they all follow the same set of design rules. This creates uniformity and makes sure all glyphs express their shared family traits.
The green area is pretty much mono line, showing no transition of thin to thick. The blue contains all of the thick-thin.
