Paint pigments pearlescent

Pearlescent lusters are commonly seen in many paints, inks, and cosmetics. The pearlescent pigment technology that brings us these unusual effects relies on a common mineral to achieve these opalescent qualities. 

The presence of mica in pearlescent pigments only partly accounts for the appearance of the pigment. A very thin layer of the inorganic oxide titanium dioxide (TiC>2) or iron oxide (Fe2C>3) or both is coated on the mica platelets. The various colors and pearlescent effects are created as light is both refracted and reflected from the titanium dioxide layers. The very thin platelets are highly reflective and transparent. With their plate-like shape, the platelets are easily oriented into parallel layers as the paint medium is applied. Some of the incident light is reflected... 

Bismuth is mainly used in the production of alloys especially of those with low melting points. It is applied as catalyst in the production of synthetic textiles, photo- and thermoelectrical parts, ceramics, glasses, and enamels. Pearlescent pigments in cosmetics and paints contain bismuth. Bi2Te3 is used as a peltier element [3-5,8,14]. 

This difference in refractive indices, arising equally on the interface between air/ oil film or oil film/water, is a prerequisite for the well-known iridescent color images in these media. Small highly refractive platelets of pearlescent pigments align themselves parallel in optically thin systems such as paints, printing inks, or plastics. Interference effects develop when the distances of the various layers or the thicknesses of the platelets have the right values. 

Pearlescent pigments are used to obtain pearl, iridescent (rainbow), or metallic effects, and in transparent color formulations to obtain brilliance or two-tone color, luster flops and color travel effects (changing with viewing angle). The most important applications are plastics, industrial coatings, printing inks, cosmetics, and automotive paints. 

These minerals have found use in a wide variety of pigments. Many pigments are based on clays, so, for example, green earths are rich in clay minerals and chlorites. Micas have been used as pearlescent paints and occur as traces in many pigments. 

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