The refractivity is also known as the refraction index. The greater the refractive index difference between the two media is, the more significant the masking effect is.
The titanium dioxide has the largest refractive index and best performance among white pigments. The refraction rate of rutile is larger than that of sharp titanium, and the performancof rutile is better than that of anatase.
In the thin film of dioxide titanium
with the high refractive index, the light has a big zigzag, short path, less light absorption, high opacity and better whiteness.
The speed of light in the titanium dioxide particles of a high refraction index is much slower than in the low refraction resin.
The scattering of light is caused by light passing through the pigment particles and by the refraction and diffraction that occur near the pigment particles.
The comparison of refractive indexes:
clay 1.65 < calcium carbonate 1.63 < zinc oxide 2.02 < ruminite 2.55 < gold red stone 2.73.
The comparison of relative hiding power:
lead white < zinc oxide < oxide antimony < powder < sulphide < rutile
The size and scattering intensity of titanium dioxide particles:
The ideal titanium dioxide particle size is 0.2-0.5 um. According to people's vision, blue and white are brighter than pure white, so they tend to produce titanium dioxide of around 0.2 um. It is possible to eliminate the inherent yellow phase in the rutile.