The Role of Whiteness Index and 3NH‘s Precision Measurement Tools

When we say white color, it appears to be easy, pure, clean, and bright. However, scientifically, there is nothing simple about the idea of being white. The level of whiteness is fundamental in industries such as paper manufacturing, textiles, plastics, and paint. 3NH is a technology leader in color measurement technology.

It provides the ability to measure whiteness, allowing industries to ensure the consistency of the product, its quality, and adherence to international standards.

The blog will explore the science of whiteness and the different whiteness indices used today. We will also look at the method of measuring whiteness using the various tests. At the end, you will know about 3NH advanced instruments, such as the NH310, ST10, and YS6002-M. They guarantee that whiteness tests are quick and accurate.

The White Colour: A Deceptively Complex Shade

White is not one color; it is the sum of all the wavelengths of visible light. The white colour scale changes with the light source, the angle of the observer, and the reflection of the surface. Diverse whiteness must be measured in industrial applications. Based on the material and application, such as that of copy paper (blue-white) and fabrics (cream-white).

The appearance of white can be influenced by:

● Light Source: Daylight vs. fluorescent vs. incandescent

● Surface Properties: Texture and glossiness

● Color Tint: Bluish, yellowish, or neutral undertones

Defining Whiteness

Whiteness does not imply only brightness, but also contains hue and saturation. This is why it has to be defined on a specialized whiteness scale. Some of the parameters that contribute to this definition include the presence of fluorescent whitening agents (FWAs), yellowing, and opacity.

In a bid to create consistency in the industries, different whiteness indices have been established. These mathematical models assist in the comparison of how a sample is close to a perceived ideal white under certain viewing conditions.

What is the Whiteness Index?

A Whiteness Index (WI) is a scientifically described measurement to quantify the whiteness color of a material in normalised lighting and viewing conditions. It is useful in the assessment of not just the brightness. But also the minor tints, which can influence perceived whiteness, like bluish or yellowish tinges. Whiteness indices are also very important in the paper, textile, plastic, and coating industries. Color uniformity and the aesthetic properties of color are important factors in the quality of the product and how the product is perceived by the consumer.

Whiteness is measured by reflectance spectrophotometers or colorimetry, and using standard mathematical models gives objective measurements. These values assist the manufacturers to keep track of batch-to-batch consistency, determine the consequences of whitening agents, and determine material degradation through age or UV exposure.

The Modern Whiteness Indices

To serve the various industries with their requirements. Some standardized whiteness indices have been established. Every index employs particular formulas, light source, and angle of observation to deliver precise and application-related whiteness assessment. The most popular indices in current color science are listed below.

1. CIE Whiteness Index

It is defined by the International Commission on Illumination and is derived by use of chromaticity coordinates and luminance under daylight. Best suited to those industries where precision is needed, such as paper and textiles.

2. ASTM E313 Whiteness Index

It is mainly applied to nearly white materials, including the illuminants such as C/2 and D65/10 and, taking into consideration fluorescence. Broadly, it is recognized in paper, textile, and plastics.

3. AATCC Whiteness Index

It is textile-specific, and it measures the brightness of fabrics following the bleaching process. Important to the appearance of garments and the efficiency of the processing of fabrics.

4. Hunter Whiteness Index

Computes whiteness based on the values of L* and b* of the CIELab color space. It is sensitive to yellowing and thus important in high precision applications such as plastic molding and paint production.

5. Ganz-Griesser Whiteness Index

It concentrates on the aging and yellowing of material over periods. This index cannot be overvalued in the case of technical textiles and research-based usage, where durability is a must.

Paper Brightness vs. Whiteness

Many assume brightness and whiteness are interchangeable, but they’re not.

Paper Brightness

Brightness is the measurement of the amount of reflectance of blue light of a certain wavelength, normally 457 nm. It is a one-step measure. Most commonly applied in paper production to measure how bright a paper surface reflects, especially when it is under a UV-rich light. That is why the paper brightness chart is most likely to concentrate on this parameter only.

Paper Whiteness

Whiteness is, however, a more complex property. It also takes into consideration chromaticity (color tone) and reflectivity over the entire visible spectrum. Also, the human perceptual perception of the material in general. It takes into account the strength and the tint of the light, which is reflected, bluish, reddish, or yellowish.

As an Example

A brightly colored paper can be rated as high in brightness. But it may still not look as white if it is a warm or yellow tone. On the other hand, paper with optical brightening agents (OBAs) may be bluer and seem to be whiter when under UV light. When exposed to natural daylight, it would behave differently. Thus, to maintain visual consistency and consumer satisfaction in such industries, it is essential to know both metrics.

Measuring Whiteness: Test Methods

Whiteness testing applies principles of physics, optics, and modeling to objectively measure the whiteness of a surface. Since whiteness may be affected by hue, brightness, texture, and even ambient light. It is essential to have agreed-upon measurement procedures and standardized equipment. The most common strategies are the following.

1. Reflectance Spectrophotometry

It is the most widespread and accurate technique of measuring the whiteness of non-transparent surfaces. It consists of placing a beam of light on the sample and recording the intensity of the reflected light in the visible range of the spectrum (normally 400-700 nm).

More sophisticated sensors and algorithms are incorporated into our devices, such as the NH310 and ST10. They translate measurements to whiteness index values such as CIE Whiteness or ASTM E313. Such tools can analyze highly complex surfaces in a fast and accurate manner and usually accommodate many geometries (e.g., d/8, 8/d).

2. Transmission Haze Measurement

Applied to transparent or translucent plastic films, plastic lenses, and packaging materials. The technique determines the amount of scattering of the light that travels through a sample. High haze means that it is less clear, and in many cases, the perceived whiteness is also lower.

Instruments such as 3NH YS6002-M measure haze, transmittance, and chromaticity. This assists manufacturers in providing visual consistency and transparency of their products.

3. ASTM and ISO Standard Methods

Whiteness testing is repeatable and comparable across the world by global standards. These standards not only define the geometry of the measurement, the calibration procedure, the condition of the observer, and the tolerances. This should be allowed to maintain data accuracy between facilities and supply chains.

Key references include:

● ASTM E313 – Defines whiteness for near-white surfaces using specific illuminants and observer geometries.

● ISO 11475 – Focuses on D65 illumination and 2° observer angle, primarily for paper.

● ISO 105-J02 – Offers a method for textile applications using fluorescent whitening agents (FWAs).

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4. Visual Comparison with White Standards

Visual comparison can be done, although not as precisely, which is still helpful in quick or in-the-field determination. Under controlled lighting conditions, a known white reference is compared to a sample in this method. In this method, a sample is referenced to a known white reference using controlled light.

The differences can be identified by the trained observers when there is no high-end instrumentation available.

Nevertheless, it is a subjective and error-prone process, so this method is more appropriate as an auxiliary one, not as a primary testing tool.

Colorimetry and White Metric Measurement

Colorimetry is the study that measures human color perception and describes it. These parameters are calculated with the help of instruments and give the number of different whiteness and yellowness indices.

Whiteness testing involves:

● CIELab and CIELuv models

● ΔE (Color Difference) metrics

● Color space transformations

Introducing 3NH’s Whiteness Testers and Color Measurement Solutions

In professional and industrial-grade color analysis, 3NH is an innovation leader in accuracy and availability. Need to measure slight changes in paper whiteness, check uniformity of products in plastic molding, or optical clarity in films and packaging? 3NH has a custom-designed instrument to satisfy each requirement.

1. NH310 High-Quality Portable Colorimeter

The NH310 is a small but hard-hitting colorimeter that fits well in the laboratory and on-site quality control applications. This instrument is designed with sound engineering and ergonomics. It offers repeatable, fast, and reliable measurements. NH310 also includes PC software that allows sophisticated interpretation of data, reporting, and linking to quality control systems.

Key Features:

● 8°/d optical geometry ensures accurate diffuse/reflectance readings.

● Dual aperture options (Φ4mm and Φ8mm) for versatile material compatibility.

● Auto black-and-white calibration enhances accuracy over long-term use.

● Supports multiple color spaces: CIELab, CIEXYZ, RGB, Luv, LCh—essential for multi-industry applications.

● Impressive repeatability (ΔEab ≤ 0.06) ensures precise batch-to-batch analysis.

● Stores up to 20,000 measurement records for efficient data management.

● Easy-to-navigate 2.8” TFT screen.

Ideal Applications: Whiteness of paper, color of plastics and injection mold, printed materials check, consistency of fabric and dye.

See Our NH310 Product for More Information

2. ST10 Spectrocolorimeter

The ST10 is the top-of-the-line portable spectrocolorimeter made by 3NH that provides ultimate precision of color control. It has a high optical architecture and a silicon photodiode array with an inbuilt sensor. Its capacity of measuring CIE whiteness and yellow index, among other subtle color changes, is what makes it invaluable in industries with high color tolerance parameters.

Key Features:

● D/8 optical geometry—ideal for complex surfaces and coatings.

● Large aperture (Φ8mm/φ10mm) for better averaging on textured surfaces.

● Outstanding repeatability (ΔE*ab ≤ 0.05) and inter-instrument agreement.

● Supports 8+ color spaces including LAB, XYZ, LUV, sRGB, Lab99.

● 3.5” capacitive touch screen with intuitive interface.

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Application Areas: It is Ideal in paints and coatings, high-end electronics, ceramics, printed packaging, textiles, and in automotive interior parts and scientific R&D settings.

Explore Our ST10 For Detailed Information

3. YS6002-M Benchtop Color Haze Meter

YS6002-M is a benchtop powerhouse that is designed to do transmittance, haze, and clarity analysis. It is suitable for transparent or semi-transparent materials. It has laboratory-grade precision with industry-grade performance and full-spectrum LED lighting.