The weight of the pigment that cannot pass through the sieve (this sieve can indicate the fineness of the pigment) is called the sieve residue. The sieve residue is expressed as a percentage of the total weight of the pigment.
The test results can also indirectly indicate the fineness of the head material and the content of large grains and impurities. The dry sieving method is only used when it is impossible to use a wet liquid and when there are corresponding provisions in the technical conditions. In all other cases, the wet sieving method described below shall be used.
The sieve is a metal cylinder rolled from white iron or copper plates, and a metal mesh (linen) is stretched at the bottom of the cylinder 1~1 and 1/2 centimeters above, and there are a certain number of holes in each centimeter of the mesh. The sides of the sieve are rolled, and the upper end of the cylinder is open (Figure 25). The tube height (tube wall) is equal to 2-3 cm, and the tube diameter is 10-15 cm.
A set of sieves mostly includes the following commonly used sieve numbers: 021;015;0125;0105;0085;0075;0063,0053;0042.
When making a sieve, the size should be calculated so that one size fits within another.
The data of the number of holes per centimeter on each number of sieves is listed in Table 11.
