The shaded bottom phase is also known as the gray paint hue, or the underlying hue. It is obviously affected by the average particle size of titanium dioxide and its scattering ability. Different particle sizes will have different color tones at different wavelengths, which can be expressed by the following formula: background color = blue tone / red tone.
When the average particle size of the titanium dioxide is 0.2 μm, it has a strong scattering force for the short-wave blue light (400 nm) in the visible light, the bottom layer of the color has a relatively blue phase, when the average particle size of the titanium dioxide is 0.4 μm, it It has strong scattering power for long-wave red light (700 nm) in visible light, and the bottom hue has a slight red phase. In the case of color picking, it is important to use titanium dioxide with the correct background color for accurate color picking. This background color difference is difficult to remedy with the color of the pigment.