How to determine the hiding power of paint?

Paint hiding power refers to the minimum amount of paint used to evenly coat the colored paint on the surface of the object so that the background color no longer appears, expressed in g/m2. After the paint, ink, etc. are evenly coated, the coating film has the ability to cover the base color of the coated surface. The hiding power is the result of the scattering and absorption of light by the pigment.

The strength is mainly determined by the following properties:

(1) Refractive index, the greater the refractive index, the stronger the hiding power;

(2) Ability to absorb light, the greater the ability to absorb light, the stronger the hiding power;

(3) Crystallinity, the covering power of crystal form is stronger, while the covering power of amorphous is weak.

With the same weight of paint products, under the same construction conditions, products with high hiding power can coat more area than products with low hiding power. In order to overcome the inaccuracy of visual inspection of the hiding power of black and white grids, the hiding power was measured with a reflectance meter. The tested sample was coated on a transparent polyester film with different thicknesses, and then dried on a black and white glass plate Measure the reflectance separately, and the ratio is the contrast ratio. When the contrast ratio is equal to 0.98, it means full coverage. The covering power can be obtained according to the thickness of the paint film. Suitable for white and light-colored paints.

Hiding power refers to the ability of the colored paint to be coated into a uniform film so that the painted surface no longer exhibits the background color. It can be expressed in two ways, that is, the minimum amount of paint required to cover a unit area (unit is g/m2), or the minimum wet film thickness required to cover the bottom surface (unit is fjim). At present, the general method for measuring hiding power is to adopt the weight per unit area method (also called the black and white grid method), and generally use black and white grid glass plates. Use a brush to evenly apply the paint on the black and white grid glass until the black and white grid is invisible. This method of weighing the paint used is simple to operate, and the production of black and white grids is also more convenient, but sometimes the end point is not easy to observe. In addition, the leveling of the product and the brush marks during operation have a certain impact on the test results of hiding power.

How to determine the hiding power of paint?