Color paste, mainly refers to the water-based color paste, which is specially used for adjusting the color of water-based paint. The water-based color paste is a kind of uniform and stable concentrated color paste formed by wetting and dispersing organic or inorganic pigments (or adding water-soluble resin), which has certain fluidity or thixotropic fluidity and strong coloring strength.

There are two kinds of water-based color paste system: one is resin free system with high pigment content; the other is resin (general resin, other single resin) system with low pigment content. Among them, the former has high pigment concentration, strong coloring power, good color development performance, good compatibility, thixotropic fluidity, generally does not cause floating color and blooming, and the selection of additives is reasonable and universal. The latter pigment concentration is relatively low, but it has good coloring power, good color development, relatively stable fluidity and viscosity. The system contains resin, so the compatibility needs to be tested, otherwise it is easy to cause the paint to float or bloom.

As a colorant, color paste affects the accuracy, reproducibility, compatibility, economy and gamut coverage of color in the integrated color matching.

As an integrated color palette, it has higher requirements in physical and chemical indicators, mainly in the viscosity and drying speed of the color palette. It needs to have good adaptability to the color palette equipment to meet the requirements of the equipment. In addition, there are more strict requirements for batch stability of color paste. The control of batch color difference is an important guarantee to achieve the accuracy and reproducibility of the system.

The influence of consistency of color paste on the system is mainly the economy of color matching and the reproducibility of color matching. The compatibility of color paste is mainly manifested in flocculation, coarsening or precipitation of pigment. These phenomena will reduce the coloring power of color paste, increase the amount of color paste, uneven distribution of color paste in the paint, etc., which will directly affect the color matching economy and accuracy.

From the color gamut point of view, the selection of color paste needs to have the types corresponding to the main colors in the hue ring to meet the gamut requirements of color matching. An integrated color matching system that fully considers the cost and performance index of the color matching system will be equipped with about x + Y color pastes to meet different needs. Among them, X is the general color paste for internal and external walls, which can meet the needs of small-scale retail, or remote engineering as a sample. Y branch is a supplementary factory high concentration color paste, taking into account the needs of color weatherability and attractive cost advantages of the exterior wall.

From the perspective of performance, the selection of color paste needs to use a variety of pigments with high resistance to the environment to meet the requirements of color matching for exterior walls. For organic pigments, due to the particularity of crystal structure and the smaller particle size of pigments than inorganic pigments, they have the advantages of bright color, high saturation and strong coloring power. But pigments are not ground as fine as possible. The smaller the particle size is, the larger the specific surface area is, the more light energy is absorbed, so the stronger the unit coloring power is. However, there are also adverse methods. The smaller the particle size, the greater the damage of water vapor, oxygen and other substances to the pigment, on the contrary, the worse the weatherability of the pigment. This is also one of the reasons why some organic pigments have larger original particle size and better weather resistance.

Therefore, the color paste for external use is not the finer the pigment, the better. Although some pastes with the same pigment index have small fineness and high coloring power, their weatherability is not guaranteed at least. Especially for the color paste of the color mixing system, its fineness should be controlled in a proper range. Proper fineness, that is to say, to achieve the best number of effective coloring particles, helps to improve the weatherability of color paste relatively.

In terms of economy, it is necessary to fully consider the use of high concentration color paste in the same color gamut to reduce the cost of color matching.