Insuring the anticorrosive protection through industrial painting
28.06.2016
The industrial paint is the most common material to be used when willing to protect metallic components. Even so there are plenty of coatings available on the market the final result of the process depends on whether there has been respected or not the entire anticorrosion procedure.
This implies:
cleaning the surfaces through blasting operations
insuring an extra layer of the surface through metallization – the procedure is recommended when high mechanical and chemical resistance are expected
correct apply of paint on the surface
Industrial painting
Conventionally a protective system consists out of a primer, an intermediary layer and a final layer that are supposed to be all compatible with each other.
The primer is the first layer that is to be applied on the clean steel surface for avoiding the appearance of corrosion and it works as a base for the other 2 paint layers. In case of primers, which contain extra powdery components such as zinc or zinc silicate, mixing and permanent stirring of the substance before application is mandatory.
The epoxy and polyurethane primers are delivered in two-component-packages. The 2 elements are to be mixed before using them, so that they chemically interact with one another. These types of materials have a limited pot life in which the paint is supposed to be applied. The polymerase process continues even after the application phase, therefore guaranteeing a chemical resistant layer on the surface to be treated. The mixing and dosage can be done manually if the pot life allows it, or automatically, while using dosing and mixing equipment.
The intermediary layer is applied in order to built the final necessary paint thickness for a better mechanical and chemical protection of the system.
The final layer is more for esthetical reasons and long-term resistance. Depending on the exposure conditions it is supposed to offer the first type of protection against light, humidity, atmospheric pollutants, abrasiveness etc.
The paint application method and the conditions under which the operation is supposed to be done might have a relevant impact on the quality and durability of the overall solution. Based on the level of viscosity, the possibility to dilute the paint, the quantity of paint that is necessary within the process, one can choose to use a conventional air spray system, an airless one or an air assisted airless one.
The air spray technology
When air spraying the paint, the substance is automatically mixed and the spray guns can be gravitationally fed.
The quality of application depends on the adjustments of the nozzle’s orifice and on the pressure of the atomization air, which should be set in accordance to the consistence and the composition of the paint while also considering the expectations related to the final thickness of the layer.
The Airless Technology
When airless applying, the paint is pumped under high pressure and while released through the airless gun’s orifice it is atomized and spread on the surface to be treated. Simply modifying the diameter of the nozzle or adjusting the pressure with which the paint is pumped out, makes the atomization process possible for series of paint types. The airless method is used when the efficiency of the painting process is the main objective, while the esthetic quality of the procedure is less relevant.
Air assited Airless technology
When using air assisted airless technology, the paint is sprayed with lower pressure than in the case of classic airless technology. The atomization takes place while the extra airflow offers more control of the process, a better quality of the final results and a better transfer rate of the paint in general.
A way of applying coatings with a high level of viscosity could be the heating of the paint instead of diluting it. The method is preferred when applying solvent free materials that are usually two-components based and that are to be mixed as near the gun as possible. These types of paints are usually utilized in the petrochemical industry.
