Pearlescent Powders

Pearl pigment powders are shiny pigments that look like pearls. They can make colors that look like those in pearls, shells, corals, and metals. We can make these pigments by coating materials like mica and quartz with metal oxides like titanium dioxide or iron oxide. The material typically comes in lamellae, making it flexible and having a smooth surface. This is similar to things we see every day, like soap bubbles and oil spills.

Along with studying pearl pigment powders, people have also found and utilized other materials as substrates for making pearl pigment powders. These include glass-based pearl powders, aluminum lamellar based pearl powders, oxide-based pearl powders, Kaolin clay, ceramic laminate, graphite laminate, and more.

① Pearlescent effect

It refers to the soft pearl-like color of pearlescent pigment powders. This is the result of multiple reflections and transmission of incident light by the titanium dioxide polycrystalline film on the mica substrate, i.e. the result of light interference.

For pearlescent pigment powders with small particle sizes, the titanium dioxide coating film coated on mica flakes is divided into many small layers like natural pearls. Therefore, when incident light shines on its surface, a silky soft light (pearlescent) appears. We refer to the optical properties of mica titanium pearlescent powders as the pearlescent effect.

② Metal flash effect

We refer to the flickering sensation caused by the specular reflection of light on a metal surface as the “metal flash effect”.

We can achieve various metallic finishes by using other metal oxide films or treating mica titanium pearlescent powders with coloring agents.

③ Perspective contrast effect

Stacking transparent metal oxide with a higher refractive index than the mica substrate on the surface of transparent mica flakes can create mica titanium pearlescent pigment powders. When light refracts, reflects, partially absorbs, and penetrates multiple times at the interface of transparent layers with different refractive indices, light interference occurs between various parallel reflected lights, resulting in a pearl-like luster and color. When light hits the reflection angle, the strongest reflected color is visible, while deviation from this angle only allows for the perception of pearl white and other colors. We refer to this phenomenon of seeing different interference colors with different investigation angles as the “perspective contrast effect”.

④ Color transfer effect

The continuous coating film made of interference color mica titanium pearlescent pigment powders can show two colors together, and this color change is called the color transfer effect. For example, a pearlescent coating made of interference-colored mica titanium pearlescent pigment powders will have a film color that changes with the curvature of the film surface. The color transfer effect displays a shift from blue to orange and from yellow to purple, i.e. from the reflection color of pearlescent pigment powders to its complementary color. With the unique “color transfer effect” of mica titanium pearlescence, we can create a range of stunning decorative effects based on specific needs.

⑤ Add-color effect

We can mix mica titanium pearlescent powders with transparent inorganic or organic pigments to color the pearlescent powders directly. The resulting colors are even more captivating. If we utilize copper phthalocyanine blue or copper phthalocyanine green for pearlescent pigment coloring, the color will not weaken but rather intensify. This is the unique “add-color effect” or “color enhancement effect” of pearlescent pigments.

⑥ 3D space effect

Pearlescent pigment powders are always transparent or semi-transparent thin sheets. When light strikes their surface, it always reflects most of the incident light, while projecting the remaining light onto the next layer of pearlescent powder lamellae, repeating the reflection and refraction of light once. This process will occur repeatedly until the substrate layer is completely reflected and absorbed. This optical property lends pearlescent pigment powders a deep 3D effect in transparent coatings. When viewed perpendicular to a point in the coating film, it’s noticeable that the pigment flakes are embedded in varying thicknesses of the coating film. We perceive the film as thick even though it is very thin.

Pearl powders are non-toxic and harmless, healthy and environmentally friendly. At the same time, they also possess features like low density, resistance to light, heat, and weather, stable chemical properties, non-conductivity, non-magnetism, and consistent physical characteristics. Therefore, pearl powders are quickly taking the place of traditional organic and metal pigments in certain industries.

By combining with regular pigments, pearlescent powders can produce a range of vivid hues with superior color clarity. In fact, people often use pearlescent pigments in combination with other pigments to enhance visual effects. Some organic pigments with high transparency, such as titanium blue, titanium green, and quinacrine red, can create vibrant and vivid colors when combined with pearlescent powders. Moreover, arranging pearlescent pigments results in a stronger reflected light color and relatively weakened scattered light color. In lighter paint coatings, the impact of this vibrant color will be emphasized. It should be noted that: The combination of two pearl colors and the mixture of two regular colors are entirely different concepts. For general pigments, every color absorbs its complementaries, whereas pearl colors incorporate complementary colors into the final color effect.

Pearlescent pigments’ exceptional chemical corrosion resistance and high-temperature tolerance make them suitable for widespread use in coatings, inks, plastics, and various industries. They provide a new color system and color quality for these products. Pearlescent pigments have low heavy metal content and comply with relevant safety technical standards. So, pearlescent pigments are suitable for food packaging and children’s toys. Acid and alkali cannot corrode pearlescent pigments at room temperature. Pearlescent pigments are non-combustible, non-hypergolic, and non-conductive, and can withstand high temperatures ranging from 600 to 800 ℃.

The unique surface chemical structure makes pearl pigments excellent in hydrophilicity and suitable for waterborne coatings. However, their lipophilicity is poor. Therefore, when used in organic systems, they have poor dispersion. So, surface treatment is necessary for pearl pigments to ensure their good application in organic systems.