For the development of the variable version of LL Geigy, designer Robert Huber ventured into the realm of duplexed fonts, also known as ‘uniwidth’: proportional typefaces whose spacing and kerning have fixed values.

With conventional fonts, the metrics and kerning values change across different weights and styles, with the spacing variations resulting in text reflow when switching weights or axes. LL Geigy Duplex is variable font based on the duplex model, where each individual glyph occupies the same amount of space across the entire weight and style range, from Light to Black, and from Roman to Italic.

This concept dates back to the early 20th century, particularly during the hot metal typesetting era, where duplex fonts made printing processes more efficient. Uniwidth typefaces were used to enable typesetters to easily switch between lighter and bolder weights, or between roman and italic styles, without reflow of text – which, at the time, was not automatic as it is in today’s layout software; it would have required the re-setting of whole paragraphs of text.

The design process of LL Geigy Duplex Variable required an in-depth study of all glyph widths, proportions, metrics, and kerning across Geigy’s entire weight range. Drawing, metrics, and kerning were thoroughly analyzed and adapted from the original Geigy fonts, resulting in a typeface that flawlessly performs in both static and animated contexts.

The elimination of layout shifts when changing font weights offers a significant advantage in applications where weights are frequently switched, such as screen-based interfaces where text or buttons may transition from light to bold or from upright to italic when hovered. The gradual variable format, in particular, lends itself well to animated type applications, where sophisticated optical effects can be achieved.

LL Geigy Duplex Variable combines one or two gradual axes (weight and slant) within one file, connecting to type history by addressing the mechanical demands of early 20th-century typesetting while adapting this concept for the 21st century.