Colorants
When a colorant is used in a formula and is observed in reflected light (light is incident on the surface and reflected to the eye), the masstone of the colorant is evaluated. When the same formulation is observed in transmitted light (i.e., the light is observed through the pigmented sheet or film), the transparency and undertone of the colorant is evaluated. When the colorant is evaluated in a combination with white pigment (generally at a ratio of 5 parts of colorant to 95 parts of white pigment), the tint tone of the colorant is evaluated. It must be understood that the undertone of a pigment (when observed in transparency) is not necessarily the same as the tint tone of the pigment when observed in combination with white [1].