A. Finish and Contrast. The characters and background of signs should be eggshell, matte, or other non-glare finish. An eggshell finish (11 to 19 degree gloss on 60 degree glossimeter) is recommended. Characters and symbols shall contrast with their background—either light characters on a dark background or dark characters on a light background. Research indicates that signs are more legible for persons with low vision when characters contrast with their background by at least 70 percent. Contrast in percent shall be determined by:
Contrast=[B−B)/B] × 100
Where B = light reflectance value (LRV) of the lighter area
and B = light reflectance value (LRV) of the darker area.
Note that in any application both white and black are never absolute; thus, B never equals 100 and B is always greater than 0.
The greatest readability is usually achieved through the use of light-colored characters or symbols on a dark background.
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