In the first step of the production process, Al2O3 (Aluminium oxide) flakes with a very smooth surface are formed. The flakes are produced using a crystal growth process. They are formed in the corundum structure (α-Al2O3). The desired flake shape is achieved by controlled crystal growth in the axial and equatorial directions. The color purity and transparency of the effect pigments obtained by coating the Al2O3 flakes with metal oxides can be attributed to the synthesis procedure yielding single-crystalline thin flakes Nitta, K., Shau, T. M. Sugahara, J. EP 763 573Sharrock, S., Schül, N. "New Effect Pigments Based on SiO2 and Al2O3 Flakes", Eur. Coat. J. (1/2) (2000) 20
