Visual Color Evaluation Essay

Attempting a visual color evaluation is to determine the degree of difference between a sample’s color and the standard color. The method for establishing the procedure is usually straight-forward and simple depending on the industry or the company’s requirements. Today, many leading companies invest time and money to ensure that their products are color matched all the time.
Color can be measured instrumentally or viewed under controlled lightings to provide an objective color evaluation. Chroma Meters and spectrophotometers are used to measure color and light booths or cabinets are often used as visual grader. A light booth is a lighting cabinet with standard light sources such as D65 (Daylight 6500K), F2 (Cool White Fluorescent), Illuminant

Hence it is important to:

Evaluate within a controlled environment of a light booth to maintain standardized lighting conditions.
Switch off all room lighting except the light source of the light booth. This is to minimize the influence of ambient light interference.

Test for Metamerism
Metamerism is a very common problem, though most people do not realize this. It occurs when a pair of sample is deemed to match under one light source but not under another. This happens when the color batch or recipe for dyes, paints, inks or other pigments is changed during production, leading to a mismatch of colors.

Metameric effects are best observed under two or more different light sources and illuminants such as daylight (D65) and incandescent light (illuminant A). Visual test can be conducted using the following steps:

Visually compare a pair of metameric sample under one light source within the light booth.
Change the light source, for example D65 to illuminant A, and observe the samples for any color mismatch.
Samples are considered metameric if they match under one light source but not under