A Paint is essentially a coating or covering material applied on metallic or non-metallic surfaces for decorative or protective purposes.
Qualities of Good Paints:
The following are basic qualities of good paints.
(1.) Good Hiding Power:
It should be capable of covering the existing surface of material uniformly and thoroughly.
(2.) Color:
After its use on outer surfaces, they are exposed to the atmosphere.
Due to the exposure to the atmosphere, it may be effected by rain or various types of radiation from sunlight, which will cause bad effects on its ‘Color.’
Good paints must maintain its color under all these conditions or in any other circumstance.
(3.) Resistance:
Paints should be chemically inert to the atmosphere. This is essential if it has to protect the underlying surface of a metal.
(4.) Easy Application:
They might have to be used over wide surface areas.
It is, therefore, necessary that it should be of such a nature that can be spread easily, smoothly, and uniformly.
(5.) Economical in Cost:
Types of Paint should be selected according to the construction, and its cost should be as low as possible. Costly paints should not be used in common constructions.
Components of Paint:
Paints are prepared by intimately mixing various components in proper proportions. Following are essential components of paint.
(1.) The Vehicle:
It is actually an oil which is dried on exposure to air. Hence it is also called a drying oil.
Such oil is unsaturated in composition. On exposure to air, it gets saturated (and hence dries out).
The drying oil or the vehicle has the capacity to keep the pigment and other components of paint in suspension or solution.
These ingredients get deposited in the film, made by the drying oil on the surface of an object.
The most commonly used vehicle or drying oils are: Linseed oil, dehydrated castor oil, bleached oil, and fish oil.
Driers are those substances which are added to drying oils to accelerate the rate of drying. They act as catalysts in the oxidation process of the drying oils.
The linoleats, resinates, and naphthalenes of metals like lead, magnesium, and vanadium are commonly used drier.
(2.) Base:
A base is a solid substance that forms the body of the paint.
It consists of a very fine powder of a suitable material such as white lead, red lead, iron oxide, and titanium oxide, etc.
The base material makes the paints film harder, stronger, elastic, and safe against cracking and moisture. It makes the paint stable against Ultra Violet Rays as well.
(3.) The Pigments:
It is a coloring material added to the above components in order to impart a desired shade and color.
Pigment is added in a finely powdered state.
In White color paints: White Lead, Titanium White, Lithophone are used as a pigment.
In Red Color: Red Lead, Venetian Red, Chrome Red, Natural Red Oxides of Iron are used as a pigment.In Yellow Color: Chrome Yellow, Zinc Chromate, Yellow Ochres are used as a pigment.
In Brown Color: Oxides of Iron is used as a pigment.
In Blue Color: Pursian Blue, Paris Blue, Ultramarine, Cobalt Blue are used as a pigment.
(4.) Solvents (Paint Thinner):
They are also called Paint thinner, which reduces the viscosity of the paints to a great extent.
Solvents (paint thinner) or added to paints in order to make its application easy, smooth, and uniform.
Petroleum, spirits, turpentine and coal tar hydrocarbons are some of the commonly used solvents or paint thinner.
(5.) Extenders:
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