Pigments, powder coatings, and inks are particulate materials present in both raw and final products. Their particle size distribution (PSD) determines the appearance, quality, functionality and processability of the final product making it a key predictor of product performance during manufacturing. In paints, for example, the PSD of pigments is a critical parameter that affects the surface finish. Within the cosmetics sector, where innovation and aesthetic impact are closely linked, colour pigments are essential. To create metallic or interference effects, pearlescence or reflections, particles must be selected based on precise size, morphology, and optical properties. Classizer™ ONE supports product formulation and manufacturing, thanks to its performance in characterizing particle size distribution, composition, shape, surfactant efficacy and stability of pigments, inks, and cosmetics powders.

Quality control and R&D – Ink and pigment manufacturers must constantly monitor the characteristics of their products to ensure consistent quality and performance for their customers. A key concern is maintaining the ink stable over time to prevent its degradation and the formation of aggregates, which could clog printhead nozzles, interrupting production. The regular analysis of oversize and out-of-spec particles is essential to limit or avoid blockages. A clogged machine means halted output and direct financial losses.

The added value of Classizer™ ONE – Some issues cannot be solved with traditional techniques. The patented technologies developed by EOS enable the monitoring of ink oversize particles with unprecedented detail. Large particles in the mixture may result from impurities, insufficiently ground powder or aggregation of smaller particles. The different cases can be distinguished because the optical properties of the particles will be different. In the first case, the impurities will have a different refractive index, in the second case the refractive index of the particles will be compatible with the value expected for the bulk material, while in the latter case the solvent inclusions will lower the effective refractive index of the measured particles. This enables the precise identification of the underlying cause of oversize particles.

The mix of a pigment and an emulsion
Ink, watercolour, and oil pigment formulations include particles with varying size distribution and material composition. Formulations of pigments in cosmetics, paints, inks, coatings, and other sectors require the dispersion of different components such as oil emulsions and ground pigments in a liquid. Analysing the pigment particle populations and identifying suspended oil droplets require the ability to distinguish different populations based on their optical properties.
The Classizer™ family of particle analysers, thanks to our patented SPES/SPES² technologies, provide the necessary information to distinguish the different types and relative concentrations of suspended materials.

A mixture of blue ultramarine and oil emulsion. The SPES technique clearly sees two different populations, that can be analysed independently.

AppCases_Pigments_Mix Pigment Emulsions2 Experimental estimation of the relative concentration of each component in a mixture of ultramarine pigment and oil emulsions.

The case of two inks mixed

Inks are liquid dispersions of pigment particles, typically containig various additives to modify the viscosity, stability, wettability or colour. Their Particle Size Distribution can affect the colour strength, surface finish, and durability of the product, and it must be monitored to ensure they are small enough to prevent clogging of printhead nozzles.
Using the EOS CLOUDS representation it is possible to isolate and analyse individual particle populations in a mixture, allowing users to evaluate and monitor the relative concentrations of each component in a given formulation.

A 50:50 mixture of white and black calligraphic inks. In the EOS CLOUDS representation, the two particle populations are clearly distinguishable and can be easily analysed independently.

AppCases_Pigments_Mix Inks 2Experimental estimation of the relative particle number corresponding to each component in the white and black calligraphic ink mixture.

Quantitative Analysis

The capabilities of Classizer™ ONE and the patented SPES/SPES² methods meet the needs of value-added applications in the characterization of inks, watercolours, and oil pigments.
SPES/SPES² data provides physical and statistical information, such as PSDs and oversize analysis. These characteristics are crucial for improving formulation quality and understanding, even in complex systems with secondary populations and mixtures.

Numerical and Cumulative PSDs of a set of watercolours.

Oversize Analysis of a set of watercolours.

Discover more > EOS Application Note AN018 SPES Classification of Inks, Watercolours, and Pigments