Color measurement of granules with the Aeros spectrophotometer

Color measurement of granules and pellets with the Aeros spectrophotometer from HunterLab

Detect color changes at an early stage, ensure quality and increase productivity

In the production of various granulates, the product is analyzed with a spectrophotometer during the manufacturing process to ensure the correct shade. A change in the color of the end product should be detected at an early stage in the process in order to be able to intervene in time and “save” the product. Production should not be disrupted or held up by this quality control.

Special measuring techniques help to carry out reliable checks during production with simple handling. With the
HunterLab Aeros
you can precisely determine the color of granules. As this non-contact measurement method is very user-friendly and the measurement results are reproducible with high repeatability, this device is recommended by HunterLab for the measurement of granules and pellets.

Non-contact measurement from above

In processing, some products take the form of pellets, granules, chips or flakes, i.e. they are not flat solids. For this reason, the product is placed in a dish for color measurement and the surface of the particles is viewed as a whole. The measurement is carried out without contact from above. Automatic height adjustment ensures the perfect distance between the sample and the sensor.

Easy handling

The simple filling of a tray without flush scraping or jogging provides the most accurate results with the highest repeatability. Due to a sufficient layer thickness of the sample in the dish, the color of the bottom of the dish demonstrably has no influence on the measurement result, even with translucent samples.

Large measuring surface due to many measurements

Granules are irregular in size and shape. Individual measurements of small surfaces would therefore deviate greatly from one another. The Aeros calculates the average value of 35 measurements in 5 seconds while the bowl rotates under the sensor. The sensor is positioned eccentrically and therefore the measuring spot is positioned close to the edge. A total surface area of up to 177.25 cm2 is therefore considered. A comparison with intermediate measurements without a measuring flash guarantees that the measurement is insensitive to the ambient light present. The following selection from a variety of optional color scales and indices has proven itself when measuring granules:

  • Color scale: CIE L*a*b* for the complete color description
  • Color index: YI E313 (degree of yellow)
  • Differences: ΔE* or ΔE*2000
  • Illuminant/observer function: D65/10

(Note: If you want to match the color at different locations, you should always use devices of the same model).


Der Gelbgradindex E313

Speziell bei transluzenten Granulaten gibt der Gelbgrad YI E313 sehr gut Aufschluss über den richtigen Verlauf des Produktionsprozesses. Ein Gelbstich bzw. eine Vergilbung des Endproduktes soll im Prozess vermieden werden. Dieser Farbindex YI E313 wurde durch die ASTM für Papier, Farbe und Kunststoff festgelegt und dient der Angabe, wie weit die Farbe einer Probe von einem idealen Weiß oder idealer Farblosigkeit abweicht. Ein höherer Wert des Gelbgrades bedeutet eine stärkere Vergilbung der Probe.


The inhomogeneity of the sample determines the choice of measuring device. Aeros is used for irregularly shaped samples of all kinds.


Would you like to know how we exactly reproduce the color values of your sample? Get in touch with us, our spectrophotometry experts look forward to hearing from you.

The blog about color measurement

All about color measurement

The HunterLab Europe company blog keeps you up to date on applications and measurement methods, product presentations and company news. Our spectrophotometry experts regularly give you an overview of the colorful and diverse world of color measurement.
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