Effect pigments based on platelets are known to the industry for quite some years now. Historically TiO2 coated natural mica products entered the industry around 1960, shortly after which other metal oxide mica pigments where added.

In the following years platelets of aluminium, synthetic mica, aluminium oxide, silicium oxide and borosilicate (glass) were added as substrate to create different effect pigments.

In GEOTECH’s portfolio natural mica (Geopearl®), synthetic mica (Geopearl® Crystal) and borosilicate (Geodiamond®) are some of the major product lines. For every product line several particle size distributions (or classifications) are in use. Based on this particle size the next very general statements can be made:

  • Large particles have a large and relatively smooth surface with a uniform reflection of incident light. This results in an excellent luster, sparkle and brilliance.
  • Small particles have smaller flat surfaces with more edges and corners. This in turn results in an increased scattering and refraction and therefore better hiding.

Colour is “introduced” by a variation in layer thickness of the TiO2 coating, starting as silver white and with increasing thickness the interference colours gold, red, blue, violet and green are obtained. Metallic like colours are formed by using Iron Oxide, replacing the TiO2. Descriptions like bronze, copper, russet and rufous belong to this family.

As mentioned GEOTECH’s portfolio consists of both natural and synthetic mica based pigments. Synthetic mica has comparable characteristics to natural mica, however it produces more vivid, clean and bright colours. Natural mica shows a more yellow-grey colour because of natural occurring impurities, like iron.

Borosilicate based pigments (Geodiamond®) produce a very clean effect with an even more brilliant sparkle compared to synthetic mica based products.

For more information, contact our Laboratory & Product Development Manager, Arthur van Rooyen avanrooyen@geotech.nl

Natural (left) versus Synthetic (right) mica