An inline quality control device for continuous measurement of fineness of grind in paint dispersion processes

• This study evaluates a new continuous grindometer for fineness of grind (FoG) measurement in pigment dispersion. • The traditional Hegman gauge shows high operator dependency and inconsistent interpretations. • A novel grindometer enables objective, in-process, and continuous (FoG) measurement. • The method performs reliably across a wide range of viscosities and application speeds. • Integration with image processing supports future automation of grind evaluation. This study investigates the performance and applicability of a newly developed, novel continuous grindometer designed to monitor the fineness of grind via scratches made by particles during pigment dispersion processes. The device offers continuous, real-time measurement and aims to address limitations of the traditional Hegman gauge, such as operator dependency and limited sampling. Comparative tests using various commercial coatings demonstrated that the continuous grindometer can produce results comparable to those of the Hegman gauge. Its performance was further evaluated during the dispersion of different pigments, confirming the device's ability to track changes in fineness over time. The effects of application speed and rheological behavior were also examined. Results showed that scratch visibility depends on both the rotational speed of the applicator and the viscosity of the sample. Optimal performance was achieved with an application speed of at least 10 cm/s and low-shear viscosities in the range of 500–50,000 cP. Overall, the continuous grindometer proved to be a promising alternative to traditional methods, offering in-process quality monitoring, increased sampling volume, and greater measurement objectivity.