To visually evaluate colors, a trial (batch) is compared to a target (standard). The standard represents the "ideal" color. For example, a customer submits a master standard to a vendor. The vendor produces a trial to match the standard. The customer and vendor must agree on the acceptable color limits, or tolerances, between the colors. Since visual assessment is the ultimate judge of acceptability, it is important that the vendor establish good communications with the customer. Physical specimens are affected by a variety of factors, such as light, heat, age and other ambient variables. Therefore, it is important to consider the following characteristics when selecting a standard. For instance:
• Stability: How is the standard affected by light, temperature, heat, age, and other ambient variables?
• Reproducibility: Can the standard be reproduced by the manufacturing process, or does it represent a one-time-only color?
• Availability: If the standard is damaged or lost, can it be replaced?
• Consistency: How consistent is the color standard from run to run?
• Uniformity: Does the standard appear uniform? Does its uniformity impact color measurement?
• Representation: Does the standard accurately represent the product color or/and surface texture, or/and gloss, or/and angular dependency attributes (e.g., metallics, pearlescents)?