HunterLab SpectraTrend HT User Manual page 105

Gray Change, as implemented, is based on ISO 105-A05:1996, Textiles - Tests for Colour Fastness - Part
A05: Instrumental Assessment of Change in Colour for Determination of Grey Scale Rating. This method
is equivalent to AATCC Evaluation Procedure 7, "Instrumental Assessment of Change in Color of a Test
Specimen." It is intended as an alternative to visual assessment as described in ISO 105-A02: 1993,
Textiles - Tests for Colour Fastness - Part A02: Grey Scale for Assessing Change in Colour, or AATCC
Evaluation Procedure 1, "Gray Scale for Color Change," and is generally used in color fastness testing. It
may be used in assessing any samples except those which have been treated with fluorescent whitening
agents (FWAs).
where
dH = dH* - D
K ab
dC = dC* - D
K ab
+
h
abT
h =
M
2
SpectraTrend HT User's Guide 3.2
- 280|  180
if |h
M
if |h - 280| > 180
M
h
if |h - h
abO
abT
The bottom half
of each pair
shows the
starting color.
The top half
shows the color
of the treated
fabric.
(Illustration from
AATCC
Evaluation
Procedure 1.)
|  180
abO
105