The production process of paints leads to the productiong of undesirable by-products or waste, which include emissions of gases, liquid and solid waste. The most important kinds of waste in this industrial sector are the liquid waste and the gases.

The equipment cleaning constitutes the main source of liquid waste in the paint industry. The production of paints that are based on solvents or water, is connected to the production of waste that remains in the walls of the reactors. The equipment, in which dyes based on a solvent, is rinsed with solvent which is reused.

In order to clean the equipment used for the production of paints based on a solvent or water a caustic solution is used. The rinsing with water does usually not remove the dye that has dried on the mixing tanks. The sewages that result from the equipment cleaning with water, constitute an important source of liquid waste in the paint industry.

Moreover, dyes that do not comply with the required specifications are produced in plants that produce special dyes. Because of its high cost of production, the products out of specifications are processed again in order to be sold.

The empty packing of liquid raw materials, which contains dangerous waste (eg solvents and resins), constitutes the main source of solid waste in the paint industry. Furthermore, a considerable amount of solid waste is the mud from sedimentation vessels, which is collected in barrels, and the waste from filtration that contain pigments that have not been dispersed satisfactorily in the produced paint.

The main gas pollutants in this industrial sector are the volatile organic substances (VOC's), the steams of acids, the nitrogen (NOx) and sulphur (SOx) oxides and the pigments' particles. The emissions of volatile organic materials are produced by the storage of resins and solvents and using them in equipment which has free surface, as mixing tanks.