,A paint for iron is, like all paints, a heterogeneous liquid system that dries quickly. It also generates a thin but elastic and resistant film on the object on it protects. It serves to prevent and limit the natural deterioration of the metal, due to atmospheric agents and rust.
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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.
Basically a paint is a mixture of the following 4 elements:
A binder: It is a polymeric resin that forms the base of the film that the paint forms by drying. The resins used as binders can be many and their characteristics greatly influence those of the paint.
A solvent: It makes the mixture fluid and allows its application to the substrate. Obviously the type used 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. They are usually insoluble inorganic salts such as silicates or carbonates.
Additives: They are special chemical compounds found in small quantities in a paint, that give it particular characteristics. Manufacturers add them during processing, to give desired properties to the dried film.
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The paint is transferred, with various systems such as brushes, and paint sprayers, on the external surface of an object. In this case iron, and completely covers the surface with a thin film.
Subsequently the solvent evaporates and the paint hardens, remaining attached to the substrate, which thus remains completely encapsulated.
Painting is usually a process that consists of several phases. It starts, in fact, from surface preparation. The next step is priming the surface with priming paint, and finally giving it one or several coats of the final paint.
Why Should Iron Be Painted?
The painting of iron, and more generally of metals, is indispensable. Not so much because it increases the aesthetic value of the object, but basically because the treatment preserves it.
Metals, especially iron, are vulnerable to the phenomenon of electrochemical, attack that is known as corrosion.
Best Metal Paint To Prevent Rust – Corrosion
Corrosion, specifically that of iron, is a phenomenon of interaction (a set of electrochemical reactions) between the metal and the elements of the environment that surround it. That tends to degrade the metal to the point of compromising its characteristics and functionality.
The corrosion process begins with the oxidation reaction, which occurs when the metal comes into contact with air and humidity. Any paint that will keep a metal surface from coming into contact with moisture, will protect it from rust.
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Rust is formed as a result of this reaction between iron and moisture. The faster the corrosion, the greater the electrical conductivity of the aqueous solution in which the described reactions take place. This 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 therefore painting. In other words, painting coats the external surface of the iron object.
The thin film coat of materials that may have different compositions, encapsulates the metal surfaces, to prevent contact with air and water.
Types of Paints for Iron
You can differentiate paints according to the type of binder, as well as the resins present in the mixture. According to this criterion we can therefore have:
Oil-Based Paint For Metal
Alkyd paints: Manufacturers make them by combining in various ways, both in quantity and quality, some basic organic compounds. These compounds are:
- fatty acids (long chains of carbon atoms linked to a carboxyl-COOH group);
- polyols (organic compounds characterized by the presence of several hydroxyl OH groups).
They are single-component, economical and versatile paints that can dry both in air and in oven. They are the most common type of iron paints. Their main disadvantage is their poor resistance to aggressive atmospheric conditions.
Acrylic Paint For Metal
Acrylic paints: These are also a very wide range. They use as binders polymers that are obtained from acrylic monomers such as acrylic acid CH2=(CH)COOH.
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Epoxy paints: They use epoxy resins as binder. Manufacturers get the polymers from monomers containing the epoxy ring. They are two-component paints in the sense that the two components must remain separate, and mixed only at the time of preparation.
They are very resistant both mechanically and to chemical attacks and atmospheric agents, but they have poor aesthetics.
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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.
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Polyurethane paints: They use polyurethane resins as binder. They are bicomponent and therefore dry due to a chemical reaction. You have to mix the bicomponents during preparation before painting.
They have good mechanical resistance, excellent resistance to atmospheric agents and chemical aggression. They also 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:
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). Moreover, passivating components (they slow down or inhibit the electrolytic reactions that trigger corrosion).
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The compounds with such characteristics that manufacturer use to make anti-rust paints are: lead minium (red lead), zinc oxide, zinc phosphate. Anti-rust paints do not usually have an aesthetically pleasing finish due to their grey or reddish color.
Best Metal Primer
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.
They do not perform this function not by covering and insulating the metal like anti-rust. They do it by by exploiting the electrochemical characteristics of the zinc filings. Zinc filing react with oxygen to create a protect compound for metals.
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.
These are used for basic paints necessary for further finishing, due to their mild anti-corrosive and anti-rust action.