GEOTECH’s portfolio consists of products with various particle sizes and by that different effects can be obtained. Descriptions like “Silk”, “Bright”, “Sparkling” or “Glittering” and others are used, focusing on particle size distributions in different ranges (examples: 1-15 µm, 10-60 µm, 20-150 µm etc).

Malvern Geotech Special Effect Pigments

In our quality control proceedings we have the option to determine the particle size distribution (or PSD) of our products, using the Malvern 3000. This machine uses a laser beam which passes through a dispersion of particles in liquid (water). Large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles.

This angular variation in intensity is analyzed in order to calculate the size of the particles responsible for creating the scattering pattern. The calculation can be done using the so called Mie theory or Fraunhofer approximation of light scattering. Finally the particle size is reported as a volume equivalent sphere diameter.

Typical reports like below can be generated giving a more in-depth insight in the products’ particle distribution.

Left to right:

Fortunately nowadays the technique is relatively fast and can be used for regular quality control activities, ensuring GEOTECH’s product quality.

For more information, contact our Laboratory & Product Development Manager, Arthur van Rooyen