What type of paint is best for metal? Paint for iron, is like all paints, a heterogeneous liquid system that dries quickly. Moreover, it generates a thin, but elastic and resistant film on the surface on which you apply it. The paint prevents and limits the natural deterioration of the metal due to atmospheric agents and oxidation.
If the system that makes up the paint contains pigments (substances that dispersed in appropriate solvents have the ability to color), we speak of enamel or paint. In this guide, we will look at all you need to know about metal paints.
What Type of Paint Is Best For Metal
Basically, paint is a mixture of the following 4 elements:
Binder. It is a polymeric resin that forms the base of the film that the paint creates by drying. The resins used as binders can be many, and their characteristics greatly influence those of the paint.
Solvent. The solvent makes the mixture fluid, and allows its application to the surface. Obviously, the type you will use depends on the resin that constitutes the binder.
Charges. They have a simple filling function, and serve to improve the aesthetic characteristics of the paint film. Further, they are usually insoluble inorganic salts such as silicates or carbonates.
Additives. These are special chemical compounds that are added in small quantities to the mixture that makes up the paint. The purpose is to give it particular characteristics during processing, or to give desired properties to the dried film.
You transfer the paint, using various systems, on the external surface of an object, in this case iron, and completely cover the surface with a thin film. Subsequently, the solvent evaporates, while the paint hardens, and remains on the surface.
Painting is usually a process that consists of various phases. It starts, in fact, from the preparation of the surface, and proceeds by giving several coats of paint even with different paint products.
What Type of Paint Is Best For Metal
The painting of iron, and more generally of metals, improves the aesthetic value of the object. Moreover, it preserves it from the phenomenon of electrochemical attack that is known as corrosion.
Corrosion, specifically that of iron, is a phenomenon of interaction between the metal and the elements of the environment that surround it. It tends to degrade the metal to the point of compromising its characteristics and functionality. The corrosion process begins with the oxidation reaction that occurs when the metal is exposed to air and humidity.
Rust is formed as a result of this reaction. Moreover, the faster the corrosion, the greater the electrical conductivity of the aqueous solution in which the above reactions take place. The conductivity increases with the presence of salts dissolved in the water. This explains why the rapidity of the phenomenon in areas adjacent to sea coasts where the air is rich in salt.
To protect the iron from corrosion, it is therefore necessary to preserve it from contact with air and water. One possible method to achieve this is by painting. In other words, it is a procedure by which you coat with a thin film of materials the external surface of the iron object. These materials may have different compositions, and they cover the iron, preventing contact with air and water.
What Type of Paint Is Best For Metal – Types of Paints for Iron
You can differentiate paints according to the type of binder, and therefore the resins present in the mixture.
According to this criterion we can therefore have:
Alkyd paint. They are a very wide range that is obtained by combining in various ways, both in quantity and quality, some basic organic compounds. Furthermore, they are single-component, economical, and versatile paints that can dry both in air and oven.
Keep in mind that they the most common type of iron paints. Their main disadvantage is their poor resistance to aggressive atmospheric conditions.
Acrylic paints. These are also a very wide range. They use as binders polymers that are obtained from acrylic monomers such as acrylic acid. Further, these are high quality paints that usually require oven drying.
Epoxy paints. They use epoxy resins as binder. These are polymers that are obtained from monomers containing the epoxy ring. In addition, epoxy paints are two-component paints in the sense that the two components are normally separated, and united only at the time of preparation.
Epoxy paints are very resistant both mechanically and to chemical attacks and atmospheric agents, but they have poor aesthetics.
Polyester paints. They have similar characteristics to the alkyd ones. However, they are at a higher step because they resist better to atmospheric agents and chemical attack.
Polyurethane paints. They use polyurethane resins as binder. Furthermore, they are bicomponent and therefore dry due to a chemical reaction. The two components are mixed during preparation before painting.
These paints have good mechanical resistance, and excellent resistance to atmospheric agents and chemical aggression. In addition, they provide an impeccable aesthetic finish.
Other differentiation of iron paints can be made according to the phase covered in the painting process. In function of this criterion we can differentiate the paints in:
Anti-rust. Their peculiar characteristic is to contrast rust and corrosion. They perform this action thanks to covering components (they isolate the iron from air and water). Also, they have passivating components (they slow down or inhibit the electrolytic reactions that trigger corrosion).
There are three compounds with such characteristics that manufacturers use in the preparation of anti-rust paints. They are lead minium, zinc oxide, and zinc phosphate. Anti-rust paints do not usually have an aesthetically pleasing finish due to their grey or reddish color.
Primer. They are paints that act as a base and as a primer for a further coat of paint with characteristics of more valuable finishes. Obviously, they must have good anti-corrosive properties.
That means they perform this function not by covering and insulating the metal like anti-rust. Rather, they carry out the function by exploiting the electrochemical characteristics of the zinc filings of which they are rich.
This, in fact, being a less noble metal than iron, works as an anode inhibiting the oxidation reaction of the iron that starts the corrosion process. A particular category of primers are the wash-primers. You use them for basic paints necessary for further finishing due to their mild anti-corrosive and anti-rust action.
Enamels. These are paints with a glassy base that not only have a protective function, as they encapsulate the object, but can also form a basis for further coatings with decorative functions. They are mixtures of silica and carbonates to which metal oxides are added, which have the function of coloring the transparent compound.