Whiteness and Yellowness

Whiteness (WI) is a measure of a visual rating of whiteness for white and near-white surfaces. Some common WI are:

• ASTM
• CIE
• Ganz-Griesser
• Hunter

WI is used in textile, plastics and paint industries for near white samples.

Color has three parameters but manufacturers of white colored products find it easier to use a single index scale when qualifying their products. There are many whiteness indices and it is important to note that for a WI to be valid, the correct WI must be used and the materials must be in similar gloss, texture, opacity and other physical properties.

Yellowness Index (YI) is an indication of the degree of deviation from white to yellow. The yellowness of ideal white is almost zero. The more it deviates from the ideal white, the larger the yellowness value.

YI is most commonly used to evaluate color changes in a material caused by wear and tear, degradation through prolonged use or exposure to environment. YI is widely used as an indication of deterioration.

Why do newspapers turn yellow over time?
Why is my white shirt glowing?