Material grades
Outdoor channel letters are continually exposed to direct sunlight and harsh weather. This exposure can have a significant impact on the effectiveness of a sign over time, particularly if the sign uses poor material grades.

Low-quality acrylic has a tendency to fade in colour, which can lead to an unsightly appearance in terms of accurately reflecting the client’s brand (see Figure 14). Instead, 4.8-mm (0.19-in.) thick colourfast acrylic is recommended, as it will help prevent damage from sunlight and other environmental factors, ensuring a bright, vibrant appearance for a longer term.

Further, some colours of acrylic and vinyl can be illuminated more effectively than others. Dark blue and dark green, for example, are generally not good colour choices for a channel letter face, as they can absorb much of the light, rather than emitting it (see Figures 15 and 16). Blue light also tends to focus just in front of the viewer’s retina, causing an undesirable halo to appear around the sign, such that legibility is reduced.

Heights and strokes
Some clients are not aware standard channel letters have specific minimum and maximum heights and stroke widths. Letter sizes outside these parameters are sometimes possible, but will often require customized fabrication.

A common minimum channel letter height is 203 mm (8 in.), while a corresponding minimum stroke width is typically 38 mm (1.5 in.). Letters that are shorter than 208 mm tend to have channels so tight, the LED modules cannot be properly installed inside. It is therefore important for sign shops to watch out for customer orders specifying a letter height less than 203 mm, as many wholesale channel letter producers will not build to that specification.

At the other end of the spectrum, channel letters can only be made so tall before they need custom structural reinforcement work. A good rule of thumb is any letters taller than 1.8 m (72 in.) will need to be custom-reinforced and are not considered standard channel letters.

John Baylis is marketing director for Direct Sign Wholesale, a channel letter vendor. For more information, contact him via e-mail at jb@directsignwholesale.com.