According to DIN 5033, colour is "a sensory impression conveyed by the eye which is triggered by rays striking the human eye".
Color as a material is a liquid coating material composed of pigments and binders. Pigments alone give colour, but they do not adhere very well. In order to give the coating strength and durability, the individual pigment grains must be glued together and anchored to the substrate. This task is performed by the binder.
There are so many pigments:
What all pigments have in common is that they do not dissolve in the binding agents of the paints. For this reason, paints are produced in mills. The mixture of pigments, binders and other additives is sent through long mill cascades until the pigments are homogeneously distributed in the paint. One possible mill design is the roller mill, in which the viscous pigment-binder slurry is homogenized between slowly rotating rollers.
The range of binding agents is also diverse. It ranges from aqueous substances such as lime or casein glue to oily substances such as linseed oil or sunflower oil and paint binders. The latter are usually liquid plastic components that form a durable film slowly or quickly after application through oxidation and polymerization. Examples of this are the widely used acrylic resin lacquers, the basic components of which polymerise to acrylic.
In addition to pigments and binders, solvents are added to liquid coating materials to make them easier to process. For example, it would be very difficult to squeeze a pure, viscous, pigment-binder mixture through the nozzle of a spray can. However, the solvents evaporate after application and do not remain in the coating.
In addition to solvents, the paints also contain various additives that determine, for example, whether the coating sets silk-matt or high-gloss.