Understanding Pigment Particle Size
Pigments provide colour to a wide range of products, from coatings and inks to plastics, cosmetics and pharmaceuticals. Manufacturers use both organic and inorganic pigments, but achieving consistent colour and performance depends on more than chemical composition alone. Pigment analysis plays an important role in understanding how particle characteristics influence the behaviour of a formulation.
Particle size can affect key properties including colour strength, dispersion, application behaviour, durability and resistance to light and weathering. Manufacturers therefore need reliable particle size measurements to monitor raw materials, optimise formulations and maintain consistent product quality.
Measuring High-Concentration Pigments
Dynamic light scattering (DLS) provides a useful technique for measuring particle size in pigment suspensions. However, high-concentration samples can present a challenge. Their high particle concentration and low light transmittance can interfere with conventional measurement approaches, making it difficult to obtain reliable results.
This application note explores the use of DLS for pigment analysis in two high-concentration pigment suspensions: a red pigment and a yellow pigment. To overcome the optical limitations associated with these samples, the analysis used a capillary sizing cell with a 1 mm internal diameter.
Reliable Pigment Analysis with DLS
The BeNano 90 Zeta successfully characterised the particle size of both high-concentration pigment suspensions using DLS technology. The capillary sizing cell helped manage the high concentration and low transmittance of the samples, allowing the system to collect reliable particle size data without requiring excessive sample dilution.
This approach demonstrates how the right measurement configuration can extend the capabilities of DLS for challenging pigment samples. By combining the BeNano 90 Zeta with a capillary sizing cell, laboratories can perform effective pigment analysis even when conventional optical measurement conditions prove difficult.
The results highlight the potential of DLS as a practical tool for investigating pigment particle size and supporting formulation development, quality control and process optimisation.
