Analysis of car paint and coatings
Content
When moving a vehicle along the street, most people look only at its design and color. Few people think why this color looks so beautiful, because there are other layers of paint with certain functions that will protect the metal from exposure to atmospheric agents and they will prevent the paint from chipping.
So, from a repair standpoint, it is important to know what role a paint, coating or finish plays, but it is equally important to determine the specific role that undercoat paints play, especially when they need to be refurbished. But first read how to remove the front door VAZ-21099if you need to weld a rack, but there are no suitable tools at hand.
Layers of car paint
Before listing the layers of paint that are applied to the car, it should be noted that there is a difference between the external component of the coating and those used for interior decoration. This separation is associated with a policy of cost reduction and is practiced by car manufacturers who have come to whom that this type of decoration is not used to finish certain structural elements. In addition, depending on the base material, the layers or coatings used are also different.
According to this last variable, the following table indicates the coatings and paint layers most common for coating each of these materials:
Steel | Aluminum | Plastic |
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Analysis of coating and paint layers
Anticorrosion coatings
As its name indicates, it is a tool that provides a new level of protection for the treated steel surface in order to protect it from chemical processes of oxidation and corrosion. This protection is carried out directly by the metal supplier.
Protection methods used in the automotive industry:
- Hot dip galvanized - steel dipped in a solution of pure zinc or alloys of zinc with iron (Zn-Fe), magnesium and aluminum (Zn-Mg-Al) or only aluminum (Zn-Al). The metal is then treated with slop heat to cause the iron to react with the zinc to obtain the final coating (Zn-Fe10). This system facilitates thicker layers and is more resistant to moisture.
- Electrolytic galvanizing immersed metal in a tank filled with a pure zinc solution, the solution is connected to electrical conductors, positive (anode) and steel is connected to the other pole (cathode). When electricity is supplied and two wires of different polarity come into contact, an electrolytic effect is achieved, which leads to the deposition of zinc in series and uniformly over the entire metal surface, which eliminates the need for metal heat. This coating does not allow to obtain layers of such a thickness, and has less resistance in aggressive environments.
- Aluminization: This is the protection of the material with boron, which consists in immersing this metal in a hot bath consisting of 90% aluminum and 10% silicon. This procedure is especially suitable for those metals that undergo hot stamping.
Phosphating and Galvanizing
To carry out phosphating, the body is immersed in hot (about 50 ° C), consisting of zinc phosphate, phosphoric acid and an additive, a catalyst that reacts with the metal surface to create a thin porous layer, which contributes to the adhesion of the following layers. Additionally provides protection against rust and corrosion.
Lubrication is performed due to the need for passivation to fill the formed pores and reduce surface roughness. For this purpose, a passive aqueous solution with trivalent chromium is used.
Cataphoretic Soil
This is another epoxy type anti-corrosion coating that is applied after phosphating and passivation. It consists in applying this layer through a process in a plating bath consisting of a solution of deionized water, zinc, resin and pigments. The supply of electric current ensures that zinc and pigments are attracted to the metal, providing excellent adhesion to any part of the car.
The corrosion paint layers described so far are unique manufacturing processes, although there are analogues, such as electro-primers, or substitutes for them, as primers are phosphating, epoxy resins or “wash-primers” that allow anti-corrosion coatings to be applied.
Anodized
This is an electrolytic process specific for aluminum parts, which allows you to get an artificial layer with the best characteristics. To anodize the part, you need to connect an electric current after the component has been immersed in a solution of water and sulfuric acid at a temperature (between 0 and 20 ° C).
Adhesive primer
This product, aims to improve the adhesion of the lower layers, which difficulties adhere to plastic and aluminum. Their use in repair repair is important to achieve this goal and ensure the durability of the applied coating.
Reinforcement
Reinforcement is a primer used in both factory and repair work, which performs the following functions:
- Protects cataphoresis.
- It is a good basis for finishing materials.
- Fills and eliminates small pores and defects that remained after grinding putty.
Sealants
This type of coating is only used in parts of the vehicle that have a seam or seal. The task of sealants is to ensure tightness at the assembly site, in order to prevent the accumulation of moisture and dirt at the junction points, and to limit the permeability of noise into the cabin. In addition, they improve the appearance of the compound, helping to obtain a more aesthetic result, and they also have anti-corrosion properties and energy absorption properties in the event of a collision.
The range of sealants is diverse and should be consistent with the application.
Coatings anti-gravel
These are paints that are applied to the underside of the vehicle to protect them from the harsh natural conditions they are exposed to in these areas (exposure to dirt, salt, rain, sand, etc.). This is an adhesive product made on the basis of synthetic resins and rubbers, which are characterized by a certain thickness and roughness; they can be used in repairs through special guns or in aerosol packaging.
Typically, this coating is present on the floor of the car, wheel arches, mud flaps and steps under the door, as well as on the ribs.
Finishing
Finish paints are the final product of the entire coating and protection process, especially in body trim. They provide the appearance of the vehicle, and also additionally perform a protective function. Generally classified as follows:
- Paints or monolayer systems: these are paints that combine everything in one. This is the system, the traditional factory worker approach where only solid colors are available. Limitation on the emission of volatile organic compounds, and difficulties in obtaining metallic colors, as well as dyeing in one color are the disadvantages of these types of paints.
- Paints or bilayer systems: in this case two products are needed to get the same result as in the monolayer system. On the one hand, on the basis of the bilayer, the first layer gives a certain shade to the part, and, on the other, there is a varnish that gives the surface shine and protects the base of the bilayer from weather conditions. The bilayer system is the most common at present, because it is used at the factory, which allows you to get colors with metallic and mother of pearl effects.
In this case, it should be noted that it is possible to get a good water-based finish, which allows you to fully comply with the law on low CONTENT of harmful volatile substances, as well as use various pigments to obtain any colors or certain effects (color pigments, metallic, mother of pearl, with the effect chameleon, etc.).
By analogy with hair spray, this product provides strength, hardness and durability higher than monolayer systems can offer. Its chemical base can be a solvent or water, and makes it easy to color in the color of mother of pearl to achieve the best effect and greater color depth of metallic mother of pearl.
Final conclusions
The various components of the car are lined with different layers of substrates and finishes to protect substrates and promote adhesion between the paint. Thus, the knowledge of the various layers of the coating and the paints that cover a particular body component is the basis for their restoration and the achievement of high-quality repairs and durable coatings that repeat the processes used at the factory. In addition, the use of quality products also contribute to this goal.
