Table 2.

National Bureau of Standards (NBS) units. Description of color variations.

National Bureau of Standards Units	Descriptions of Color Changes	NBS = 0.92 × ΔE*
0.0–0.5	Trace. Extremely slight change
0.5–1.5	Slight. Slight change
1.5–3.0	Noticeable. Perceivable
3.0–6.0	Appreciable. Marked change
6.0–12.0	Much. Extremely marked change
12.0 or more	Very much. Change to other color