is the standardized range of colors against which the colors of petroleum products may be compared. There are a number of widely used systems of color scales, including: ASTM scale (test method ASTM-D-1500), the most common scale, used extensively for industrial and process oils; Tag-Robinson colorimeter, used with solvents, waxes, industrial and process oils; Saybolt chromometer (ASTM-D-156), used with white oils, naphthas, waxes, fuels, kerosene, solvents; Lovibond tintometer, for USP petrolatums, sulfonates, chemicals; and the Platinum-Cobalt (APHA) system (ASTM-D-1209), for lacquer solvents, diluents, petrochemicals. These scales serve primarily as indicators of product uniformity and freedom from contamination.