The following characteristics can be used to gauge a pigment's performance:
The Hue of the Pigment
A pigment's color is primarily influenced by its chemical composition, which is established by the selective absorption and reflection of different light wavelengths at the pigment's surface. All of the light wavelengths are partially absorbed by colored pigments.
Color Intensity
When selecting a pigment, color intensity must be taken into account. The ease with which a colored pigment retains its distinctive color when combined with another pigment is known as color strength. Less pigment is needed to obtain a typical depth of shade the stronger the color.
Chemical Composition
It is one of the elements that affect how strong a pigment's color is. The color intensity of organic pigments is influenced by their capacity to absorb specific light wavelengths. Color intensity is increased in molecules with high conjugation and high aromaticity. High color strength can be seen in inorganic pigments that are colored by the presence of metals in two valency states. They are poorly colored in contrast to those that contain a cation trapped in a crystal lattice.
Particles' Size
The intensity of a pigment's color is also influenced by particle size. Smaller particles produce colors with greater power. The primary factor affecting the particle size of pigment crystals is the manufacturing process. Manufacturers of pigments are essential. By stopping crystal formation during synthesis, they can minimize the size of the particles and improve color strength through effective dispersion.
The strength of the paint's color is also greatly influenced by pigment dispersion. In fact, it gives the finer particles colloidal stability, preventing flocculation and utilizing their full intrinsic color power.
Resistance to Heat
At temperatures typically associated with coatings, few pigments break down. However, pigments become more soluble at higher temperatures, which might result in shadowing. Heat stability and solvent resistance are thus tightly connected for organic pigments. As opposed to polymorphic pigments, which may react to heat differently depending on the different crystal modifications, highly crystalline pigments are typically more heat resistant.
Light Fastness
The entire pigmented system, not simply the pigment, is considered when evaluating light fastness. The degree of protection that the binder gives the pigment varies, therefore the same pigment usually exhibits better light fastness in a polymer than it does in the paint.
Climate Stability
The qualities of coloring pigments that are weather-resistant should be chosen for outdoor applications. Weatherability, which is closely connected to light fastness, adds the additional factor of atmospheric conditions. Pigments that are resistant to the elements are typically also lightfast, though this is not always the case.
Insolubility
A pigment must not react with any of the paint's ingredients, such as crosslinking agents, and it must be insoluble in the vehicle.
Even while the paint is drying, which is typically done at high temperatures, pigments must maintain their qualities. The pigment must also continue to be unaffected by the substrate as well as any agents it comes into touch with, such as water, which may only be present as condensation, or acidic industrial atmospheres, once it has dried into the film.
