We have been offering Pearl Inks, which gives pearl like color and brightness. And our new product called STELLA ink is a new version of pearl ink, which can provide brighter and clearer color. It has a special standard color which can change color by view angle.
Today we explain about the color forming mechanism and special features of our Pearl inks and STELLA ink.
1. Mechanism of Pearl ink color forming
Surface layer of natural pearl is made of multiple alternating transparent layers of protein and calcium carbonate.
Incident light goes into the layers and refracts at the boundary faces of these layers. The reflected light at these faces interfere each other and provide the typical pearl color and gloss as shown in the figures written under.
Pearl pigment utilizes this principle. Multiple layers of low refraction factor materials (such as mica, SiO2 or Al2O3 etc.) and high refraction materials (metal oxides such as TiO2 or Fe2O3) will provide pearl color.
2. Pearl Gloss and interference color
2-1. Pearl Gloss
Pearl pigment is a transparent or semitransparent flake and when coated the flake settled in the ink layer as parallel layers. Multi-layer reflection and interference provides pearl like color and gloss.
When light get in a thin layer and reflect at the top surface and bottom surface, both light rays may interfere and provide slightly changed light and gloss. When phases match light will be strengthen, and when phases don’t match, the light will be weaken. And this interference will give pearl color and gloss.
2-2. Interference color of Pearl pigment
Different thick ness of the pearl pigment will provide different visible color like rainbow.
There is a equation as under.
Different interference color can be got by changing thickness of the metal oxide layer shown as under.
3. Special Features of STELLA Pearl pigment
- Brighter color with less scattering of the light.
- As the pigment diameter set in a shallow range, give better pearl gloss.
- As the diameter of pigment is smaller than usual pearl ink (5-50 micron), can be printed with high mesh screen.