ANSI/TAPPI T 1216 sp-12
White is the color of purity or freshness and of cleanness. The consumer judges the whitest shirt to be the freshest and cleanest and automatically selects it from several on display. In some products, whiteness is not only psychologically associated with purity, but is actually an indicator of freedom from contaminants, and as such can be a measure of the quality of the product. Good white base colors are necessary where products are to be dyed, printed, or otherwise colored. The cleanness, brightness, and full range of color in color printing depend to a large extent upon the whiteness of the base paper.In physical terms, a white surface is one which reflects strongly (usually more than 70% throughout the visible spectrum. The higher and more uniform this spectral reflectance, the whiter the surface usually appears. From the point of view of geometry, a white surface is one that reflects diffusely in all directions. Mirrors, because they reflect only opposite the direction of illumination, are not called white, although a good mirror reflects strongly throughout the visible spectrum and would thus be judged white by its spectral reflectance curve.