Appendix to Subpart F of Part 655--Alternate Method of Determining the
Color of Retroreflective Sign Materials
1. The FHWA Color Tolerance Charts provide that conventional color
measuring instruments such as spectrophotometers and tristimulus
photoelectric colorimeters should not be used for measurement of
retroreflective material colors and that such materials should be
evaluated visually using the Color Tolerance Charts and paying strict
attention to prescribed illumination and viewing conditions.
2. As an alternate to visual testing, the diffuse day color of
retroreflective sign material may be determined in accordance with ASTM
E 97, ``Standard Method of Test for 45-Degree, 0-Degree Directional
Reflectance of Opaque Specimens by Filter Photometry.'' Geometric
characteristics must be confined to illumination incident within 10
degrees of, and centered about, a direction of 45 degrees from the
perpendicular to the test surface; viewing is within 15 degrees of, and
centered about, the perpendicular to the test surface. Conditions of
illumination and observation must not be interchanged.
3. Standards to be used for reference are the Munsell Papers
designated in Table 1 or Table II, attached. The papers must be recently
calibrated on a spectrophotometer. Acceptable test instruments are:
a. Gardner Multipurpose Reflectometer or Model XL 20 Color
Difference Meter,
b. Gardner Model Ac-2a or XL 30 Color Difference Meter,
c. Meeco Model V Colormaster,
d. Hunter lab D25 Color Difference Meter, or
e. Approved equal.
4. Average performance sheeting is identified as Types I and II
sheeting and high performance sheeting is identified as Types III and IV
sheeting in Standard Specifications for Construction of Roads and
Bridges on Federal Highway Projects \3\ (FP-79, Section 633).
---------------------------------------------------------------------------
\3\ This document is available for inspection and copying as
prescribed in 49 CFR part 7, appendix D.
Table I--Color Specification Limits and Reference Standards, Types I and II Sheeting
--------------------------------------------------------------------------------------------------------------------------------------------------------
Chromaticity coordinates \1\ (corner points) Reflectance
---------------------------------------------------------------- limits (percent
Color 1 2 3 4 Y) Y Reference \3\ standard
--------------------------------------------------------------------------------- (munsell papers)
x y x y x y x y Minium Maximum
--------------------------------------------------------------------------------------------------------------------------------------------------------
White \2\................................ .305 .290 .350 .342 .321 .361 .276 .308 35 -- 6.3Gy 6.77/0.8.
Red...................................... .602 .317 .664 .336 .644 .356 .575 .356 8 12 8.2R 3.78/14.0.
Orange................................... .535 .375 .607 .393 .582 .417 .535 .399 18 30 2.5YR 5.5/14.0
Brown.................................... .445 .353 .604 .396 .556 .443 .445 .386 4 9 5.OYR 3/6.
Yellow................................... .482 .450 .532 .465 .505 .494 .475 .485 29 45 1.25Y 6/12.
[[Page 248]]
Green.................................... .130 .369 .180 .391 .155 .460 .107 .439 3.5 9 0.65BG 2.84/8.45.
Blue..................................... .147 .075 .176 .091 .176 .151 .106 .113 1.0 4 5 8PB 1.32/6.8.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The four pairs of chromaticity coordinates determine the acceptable color in terms of the CIE 1931 standard colorimetric system measured with
standard illumination source C.
\2\ Silver white is an acceptable color designation.
\3\ Available from Munsell Color Company. 2441 Calvert Street, Baltimore. Maryland 21218.
Table II--Color Specification Limits and Reference Standards, Types III and IV Sheeting
--------------------------------------------------------------------------------------------------------------------------------------------------------
Chromaticity Coordinates \1\ (corner points) Reflectance
---------------------------------------------------------------- limits
Color 1 2 3 4 (percent Y) Y Reference \3\ standard
-------------------------------------------------------------------------------- (munsell papers)
x y x y x y x y Min. Max.
--------------------------------------------------------------------------------------------------------------------------------------------------------
White \2\................................. .303 287 .368 .353 .340 .380 .274 .316 27 ...... 5.0PB 7/1.
Red....................................... .613 .297 .708 .292 .636 .364 .558 .352 2.5 11 7.5R 3/12.
Orange.................................... .550 .360 .630 .370 .581 .418 .516 .394 14 30 2.5YR 5.5/14.
Yellow.................................... .498 .412 .557 .442 .479 .520 .438 .472 15 40 1.25Y 6/12.
Green..................................... .030 .380 .166 .346 .286 .428 .201 .776 3 8 10G 3/8
Blue...................................... .144 .030 .244 .202 .190 .247 .066 .208 1 10 5.8PB 1.32/6.8.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The four pairs of chromaticity coordinates determine the acceptable color in terms of the CIE 1931 standard colorimetric system measured with
standard illumination source C.
\2\ Silver white is an acceptable color designation.
\3\ Available from Munsell Color Company, 2441 Calvert Street, Baltimore, Maryland 21218.