Color measurements are typically conducted to determine the yellowness of plastic and how the degree of yellowness changes. Color analysis can also be conducted to determine color values and ensure consistency and uniformity between lots.
This standard is used to determine Yellowness Index (YI), CIE X, Y, Z, and Hunter L, a, b, or CIE L*, a*, b* for plastic pellets. It uses a three number system to quantify color as accurately as possible. This color measurement value does not directly relate to exact measurements of molded parts from the pellets tested as processing can alter colors. Color comparisons between resins can be made if they are of the same base material and similar in size and shape. A colorimeter is used for this testing.