Transparent Functional Pigments

Transparent inorganic pigments are conveniently divided into two groups colored and colorless. The colorless pigments, which do not absorb in the visible light range, are functional nano-materials with specific properties that are described in the sections below. The colored pigments may also possess these functional properties. 

However, the transparency number is not only a function of pigment and vehicle it usually changes with the thickness of the layer (e.g., the pigment surface concentration). The transparency number of a sample which is applied at a thickness somewhere in the interval between two limits hi and h2 is calculated as follows ... 

Surveys of shallow lakes and ponds in eastern Antarctica have revealed that modern sedimentary environments preserve fossil pigments and that the abundance of photo-protective compounds increases as a function of algal exposure to UVR (Hodgson et al. unpublished). For example, the Larsemann Hills region (69°23 S, 76°53 E) is the second largest of four major ice-free oases on the east coast of Antarctica and contains more than 150 lakes and ponds. Minimal cloud cover, very transparent waters 0.21-0.35 m [117]), and a 2-3 month... 

Function Colorants act either by absorbing parts ofthe spectrum and reflecting other parts (solid pigments, dyes), or by transmitting only certain wavelengths (transparent colours) these effects can be combined with multi-layer structures, also using interference patterns to achieve an effect... 

The main reason for incorporating pigments into plastics is to introduce colour (including black and white), either for aesthetic reasons and market appeal or because of functional demands. However, the optical role of a pigment can extend wider than simply providing colour, because it plays a decisive part in determining whether the medimn is opaque or transparent. 

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