Pearl luster effect

Pearl luster pigments, which can be natural or synthetic, show outstanding qualities of luster, brilliance and iridescent color effects based upon optically thin layers. This visual impression develops by reflection and scattering of light on thin multiple layers. In nature this is not limited to pearls and mussel shells alone there are a multitude of birds, fish, precious stones and minerals, even insects which demonstrate a pearl luster effect. Experiments to understand the optical principles of natural pearl luster demonstrate that the brilliant colors are based upon structured biopolymers and upon layered structures which are developed by biomineralization. 

A) conventional pigment B) metal effect pigment C) natural pearl D) pearl luster pigment... 

This difference in refractive indices, arising equally on the interface between an 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 pearl luster 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. 

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

The physical background of optical interference effects has been the subject of many publications [5.122-5.125, 5.127-5.130]. The optical principles of pearl luster (interference) pigments are shown in Figure 5.16 for a simplified case of nearly normal... 

Color effects depend on the viewing angle. Pearl luster pigment platelets split white light into two complementary colors that depend on the platelet thickness. The reflected (interference) color dominates under regular (maximum) reflection, i.e., when the object is observed at the angle of regular reflection. The transmitted part... 

Special effect pigments are used as colorants or part of color formulations for all systems where traditional pigments are applied, but where additional color depth, brilliance, iridescence, color travel, and other spectacular effects are required [5.122, 5.123]. Mica-based pigments dominate their combination of pearl and interference effects, brilliance, stability and behavior in different application systems is as yet unsurpassed. Pearl luster pigments require transparent or at least translucent binders. Formulations with absorption pigments have to take their transparency and color mixing rules into account... 

Figure 71. Optical principles of conventional and luster pigments A) Conventional pigment that absorbs and scatters light B) Metal effect pigment with complete regular reflection C) Natural pearl composed of alternating layers of protein and CaC03 D) Nacreous pigment the pearl is simulated by parallel orientation of the pigment platelets...

Ironically, one way in which our industry has created more value is 1 making plastic look more like the traditional materials they replaced glass, wood, stone, and metal. To many consumers plastic has stood for artificial and cheap. As discussed in many of the papers in the first section of this collection ( Pigments and Dyes ), the industry has responded with special effects colorants to give plastic the luster and iridescence of pearl, the rich sheen of gold and silver, or natural appearance of wood, stone, or leather. This section also contains a pair of timely articles covering health and safety aspects of plastics colorants. 

Figure 7-1 illustrates the various optical principles of conventional pigments (absorption pigments), metal effect pigments, and pearls and pear] luster pigments. In the case of absorption pigments, the interaction with light is based upon absorp-... 

Uses Personal care surfactant cold pearl cone, producing vibrant pearl at cost effective cone. for shampoos, liq. soaps, bubble baths contributes elegant high luster pearlescent appearance... 

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