Paint covering power

[View:1845 ] [Update:2013-6-15]

   Paint covering power refers to paint (or contain a material into a membrane material; xu decorated on the surface, in the surface cover accessories. Paint covering power is: the pigments in paint coating can cover up that under the surface of the coating, so that it does not show through the paint film. Paint covering power using numerical said, commonly used every square meters of area needed to cover grams of paint.

The strength of the material covering power, influenced by the following factors:

(1) paints and paint binders both the difference between the refractive index

  Dispersed pigments in paint binders equals the refractive index of refractive index and paint, pigment appears is transparent, that doesn't cover. Paint the refractive index of refractive index is greater than the paint, pigment present a cover. Force. The more the difference between the two, paint covering power is stronger. , when the light from one medium into the second medium, light in the space of the interface of two medium depends on the refractive index of two kinds of medium. If the refractive index of the two are equal, the speed of light in the interface will not change. In this case, the light won't be reflected on incoming medium surface, all into the medium, but the latter (medium) appear is transparent. If light from a low refractive index medium into the another larger refractive index medium, its speed will change, in this way, the part will light refraction phenomenon, which changed the direction of the it, just go into the second medium; And the other part of the light, will be reflected in the latter on the surface of phenomena, so the pigments is visible, medium is opaque. Hugh quality paint, pigment or low refractive index, with covering power is very weak in the paint, that is because of their low refractive index, only a slight more than paint binders of refractive index; Qin white powder and zinc oxide used in paint is shown in the strong hiding power, is because of their refractive index is larger, it is more than the paint because of the difference of refractive index is larger.

(2) the paint back to cover it

  Coating depends not only on the amount of light reflection, but also depends on the correlation on the coating on the surface of the light absorption ability. Carbon black completely don't reflect light, like absorbs all the light on it, therefore, its hiding power is very strong. Colorful opaque pigment cover ability strong or weak depends on the choice of light absorption performance. They also

(3) a suitable particle size and dispersion of material

   Pigment dispersed well, make the particles become smaller, more reflection area, thus covering some of the paint covering power but the relationship has a certain limit, namely when the size of pigment particles become half the wavelength of light, such as, came to the limit. Because in this case, the light will penetrate the particles without being reflected. Such particles would appear is transparent.

(4) the pigment of crystal shape

   Some paint covering power as there are different with their crystal structure, such as the covering power of inclined Fang Pin form chrome weaker than the monoclinic crystal shape. Stick or paint covering power, depends on the stick and covering power of each composition. But cannot be calculated according to the laws of the bonus. Such as hiding power of white pigment, by adding filler and reduce the phenomenon is not significant. Zinc oxide mixed with talcum powder pigment composite, the hiding power, compared with the two kinds of pigment in addition method to calculate out of hiding power is great. So we can add extender pigment in some paint, to reduce the cost of paint, hiding power reduction did not lead it.