Pearlescent color effects

Colorability is another reason IDs select plastics for many products. Molding color into a product eliminates finishing and painting operations, thus reducing costs. Beyond cost, integral color also masks the nicks, chips and scratches that impair appearance during the life of the product. Color effects are almost limitless. Transparent, translucent, pearlescent, fluorescent, or marbleized colors are readily available for use in plastics. 

Synthetic or natural pigments used to achieve lustrous, brilliant, or iridescent color effects by interference on thin optical films are called nacreous or pearlescent pigments [5.190]—[5.194]. They were originally used to simulate the appearance of... 

In order to understand how three distinct colors from one pigment are possible, it is first necessary to understand the optical properties of pearlescent and interference pigments and also the optical properties of absorption colorants. The manner in which these reflect light differs and this forms the basis of the three color effect. 

The colors found in industry today can be grouped into four main categories of finishes solid or straight shade colors, metallic colors, pearlescent colors and special effect colors. Any... 

Color effects depend on the viewing angle. Pearlescent pigment platelets split white light into two complementary colors that depend on the platelet thickness. 

Colorants have been developed for special effects. Pearlescent or iridescent give an attractive appearance. They are often used for coating paper (e.g., cosmetic packaging). The pigment consists of thin platelets, less than 1 pm thickness, which have a high refractive index, e.g., mica coated with Ti02. 

Pearlescent pigments contain small flakes or platelets of the mineral mica that are additionally coated with a very thin layer of titanium dioxide. The simultaneous reflection of light from many layers of small platelets creates an impression of luster and sheen. By varying the thickness of the coating on the surface of the mica particles, pigment manufacturers can achieve a range of colors for the pearlescent effect. 

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... 

Colorant A pigment, dye, or other chemical that imparts color (including black and white) or any special effect appearance to a polymer. These special appearances could be metallic, pearlescent, stone and fleck, flourescent, phosphorescent, thermochromatic, or photochromatic. 

By combining metallic pigments with pearlescent pigments, unique optieal effects can be achieved. Small additions of metallic pigments to material colored with pearlescent pigments will improve the hiding substantially. 

Multi-Angle Spectrophotometers for Metallic, Pearlescent, and Special Effects Colors... 

These type of instruments perform well in quality control situations where standards and samples have similar textures and gloss levels however they only evaluate color at a single angle. Therefore these instruments do not give the full detail of the appearance of a color at multiple viewing angles as would be required with metallic pearlescents or special effects colors. 

The advantage of a sphere instrument over 0/45 is that most sphere instruments can be operated in the included and excluded modes. In quality control of many materials we can first determine if a given sample looks different by evaluating the excluded data. If different, we can then examine the included date to see if the formula needs to be adjusted. The advantages of a sphere instrument have many applications in multiple different applications within the paint, plastics or textiles industries. But unfortunately the sphere geometry is inadequate in determining color differences in metallic, pearlescent or special effects colors. 

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