In industrial production and quality control, color consistency is one of the core elements determining product quality. Whether it is the metallic paint for automobile coating, the dyeing effect of textile fabrics, or the ink matching in packaging and printing, subtle color deviations may lead to cost waste or damage to brand image.

The LAB color space defines colors with a three-dimensional model:

1. Lightness (L): It indicates the lightness or darkness of a color, ranging from 0 (pure black) to 100 (pure white).

2. Hue and Saturation (a and b):

• The a-axis represents the red-green tendency, with positive values leaning towards red and negative values leaning towards green;

• The b-axis represents the yellow-blue tendency, with positive values leaning towards yellow and negative values leaning towards blue.

It is a globally recognized standard and supported by most modern color measurement equipment. Color is quantitatively analyzed by measuring Lab values with instruments.

Color evaluation will change based on how a sample is viewed.  A 45° viewing angle to the source is recommended to reduce shading and achieve consistent comparison.

To quantify color change, take the original L*a*b* values of a sample, and reread after exposure or processing. Compute the difference as 1/2(Emut1 Emut2). The larger the value of ΔE, the more obvious the change of color is, which can be used in quality or stability testing.

The Colour Assessment Cabinet (CAC) is a controlled environment used for the visual evaluation of color wherein the light sources are consistent.

Flickering lamps, color shifts, and uneven lighting are common faults, which can be corrected by changing the tubes, cleaning the interiors, and re calibrating the light system.

The gloss of the paint is defined by the measurement of light reflection at the surface of the paint with the help of a gloss meter. The angle and quantity of light reflected determine the level of gloss, with smoother and reflective surfaces having a higher level of gloss.

A colorimeter is sufficient for basic, routine color checks, while a spectrophotometer is needed for precise, comprehensive color analysis—here’s the clear breakdown:

When a Colorimeter is Sufficient

1. Simple color matching needs: Ideal for checking if a sample matches a predefined standard (e.g., basic paint batches, plastic parts with solid colors).

2. Consistent lighting conditions: Works well when measurements are done under fixed, standard light sources (no need to account for varied light effects).

3. Cost-sensitive, high-volume tasks: Perfect for production lines requiring fast, low-cost color checks without advanced data analysis.

When to Use a Spectrophotometer

1. Precise color quantification: Necessary for measuring Lab values (lightness, red-green, yellow-blue axes) or detecting subtle color deviations (critical for automotive coatings, high-end textiles).

2. Complex color analysis: Required for metallic/pearlescent finishes, transparent materials, or samples with gloss/texture variations.

3. Compliance and documentation: Essential when precise color data (spectral curves) is needed for quality audits, regulatory compliance, or brand color standardization.

Take into account the measurement range, type of samples, needed precision, any relevant standards, and your industry.

Keep light booths clean, maintain the light source lamps, readjust the calibrated light source, and ensure that dust and fingerprints do not settle on the viewing area.

The color measurement theory is the quantification of the interaction of materials with light, either absorption, transmission, or reflection. It employs standard colour spaces (such as CIELAB) and devices (colorimeters, spectrophotometers) to code the visual colour into objective and reproducible data.