Principles of Colour and Appearance Measurement

8

Issues in measuring whiteness and fluorescence

Abstract:

Whiteness and yellowness are very important indicators of product quality. While whiteness represents purity and cleanliness, yellowness indicates degradation of material or the presence of impurities. In our environment, the colour white is the most encountered. Though the reflection by whites is very high throughout the visible wavelength, the substances reflecting more blue light appear whiter than those reflecting more yellow light. In other words, whiteness depends on the hue of the object. Whiteness of the objects, especially textiles, can be increased by bleaching with oxidising and/or reducing agents, or by adding a minute quantity of blue or violet colorant. The third way of improving ...