Channel Letters: Designing for LED illumination

Smaller letters with very narrow strokes can be produced as raised, illuminated characters integral to the face of a sign panel.

Cast metals
Both cast aluminum and bronze have been traditional choices for letters, logos and plaques, as they convey a sense of sophisticated quality and permanence for banks and other institutions, but LEDs have helped update them with halo lighting for better nighttime visibility. Cast metal letters are produced with a ‘cavity’ in the back for the lighting modules, with a protective rear panel easily added. They can also be custom-designed for special projects. A halo effect is possible at a depth from 13 to 76 mm (0.5 to 3 in.) or greater. A wide variety of painted, brushed, anodized, oxidized, patina and polished finishes are available.

Illuminated CAB letters are thermoformed with a slight edge radius. They are produced with a two-part construction—i.e. faces and cans—and can be face- or halo-lit. For face-lit letters, a partially illuminated return will create a dramatic effect.

CAB is easily customizable to create letters, logos and panels as small as 230 mm (9 in.) tall. The shallowest depth for proper lighting with LEDs is approximately 51 mm (2 in.). The physical size of the LED modules and the thickness of the plastics are the main factors limiting the size of individual letter strokes, but they can be as narrow as 25 mm (1 in.). Smaller letters with very narrow strokes can be produced, but instead of being individually mounted characters, they can be raised, illuminated characters integral to the face of a sign panel. Intricate designs and accents can be created by adding vinyl or printed graphics to the face.

Illuminated acrylic channel letters provide a high-end but low-profile appearance. They can be produced by precision machining or fabricating cast translucent acrylic.

Precision-machined acrylic offers a refined, sharp edge, trimless face and well-diffused light for letters and logos as small as 203 mm (8 in.) and up to 711 mm (28 in.). In addition to the face or back being lit, a 4.8-mm (0.19-in.) plate edge is illuminated for a more dramatic effect. Stroke widths can vary from 22 to 127 mm (0.87 to 5 in.).

Fabricated acrylic further extends the trimless look by supporting face, halo and/or return illumination. Pieces are precision-routed and hand-fabricated with buffed edges and range from 305 to 914 mm (12 to 36 in) tall and 33 to 102 mm (1.5 in to 4 in) deep. Letter strokes can be as narrow as 38 mm (1.5 in) and as wide as 457 mm (18 in) when illuminated.

The versatility of LEDs
LEDs can be used in channel letters in many ways, from populating recessed cavities to integrating with polycarbonate backings, from diffusing light with acrylic through the face and returns to securing lights to white backs with double-faced tape and hold-down blocks. And as LED products continue to evolve, they will be able to support even more options for illuminated sign design. The possibilities will only expand further.

Tim Bauer is the sign product manager for Gemini, which manufactures dimensional letters, logos and plaques for sign professionals. For more information, contact him via e-mail at

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