An ink trap is a feature of certain typefaces, where the corners or details are removed from letterforms. Upon printing, ink naturally spreads into the removed area; without ink traps, the excess ink would blob and ruin the crisp edge.

Ink traps are typically only needed for small point sizes and are usually only found on typefaces designed for print on newsprint. These kinds of fonts are applicable for things like classifieds, telephone books.

(Some) Ink Trap Fonts

• Kurier
• Bell Centennial
• Tang

Kurier was created as a typeface destined for newspapers and other kinds of press typeset using the linotype technology. So, it had a classical triad of fonts (normal, italic and semi-bold) adapted for linotype matrices. Particular letters and other characters were designed in fields corresponding the to width units used in that technology. By the design principle the types had to endure a series of technological processes destructive to their graphic shape, for instance: casting a row from a linotype metal alloy, so-called burning of brass matrices during casting, preparation of duplicate printing forms (stereotypes), printing on rotating machines with the use of a liquid paint on low-quality press paper (from rolls). All that contributed to the provision of adequate light inside and between letters as well as of the so-called paint traps at certain crossings of the character elements in the design.

The types were to be produced by the Katowice Linotype Matrices Factory. The full documentation from the Centre of Printing Types was sent to the Factory. However, the Kurier types were never produced industrially. The so-called hot metal typesetting technology of texts reached its end during the eighties and the fall of the Matrices Factory.

The present printing technologies do not impose the above mentioned limitations. Nevertheless, the aesthetic quality of the typeface inclined me to making of the digital version of the Kurier font. An alternative version, called Iwona, without the paint traps, was also made.

Kurier and Iwona, Janusz Marian Nowacki, http://jmn.pl/en/kurier-i-iwona/

AT&T’s brief called for a typeface that would fit substantially more characters per line without loss of legibility, dramatically reducing the need for abbreviations and two-line entries, increase legibility at the smaller point sizes used in a telephone directory, and reduce consumption of paper. Bell Centennial was designed to address and overcome most of the limitations of telephone directory printing: poor reproduction due to high-speed printing on newsprint, and ink spread which decayed legibility as it closed up counterforms. Carter's design increased the x-height of lowercase characters, slightly condensed the character width, and carved out many more open counters and bowls to increase legibility. To anticipate and blunt the degradation caused by ink spread, Carter drew the letters with deep ink traps, designed to fill in as the ink spread onto newsprint fiber, leaving the characters' counterforms open and legible at small point sizes. Printed in the smaller point sizes used in telephone directories, the ink traps are not visible, having done their job; filling in and smoothing out the character stroke. However at larger point sizes, and on coated paper stock there is not enough ink spread to fill in the traps and the shape of the traps remain noticeable. Bell Centennial is an example of a typeface designed to address a particular need, much like Chauncey H. Griffith's Bell Gothic (AT&T's earlier telephone directory face); Adrian Frutiger's Frutiger, designed for signage at Charles De Gaulle Airport; or Erik Spiekermann's FF Meta Sans commissioned by the Deutsche Bundespost (the German federal post office), but not adopted. Bell Centennial is only one of several typefaces Carter designed to address specific technical limitations, including CRT Gothic (1974), Video (1977), Georgia (1996), and Verdana (1996).

Bell Centrennial, Wikipedia, http://en.wikipedia.org/wiki/Bell_Centennial